Removal of non-retinal opthalmic reflections in retinal imaging

ABSTRACT

System and Method pertaining to the modification and integration of an existing consumer digital camera, for example, with an optical imaging module to enable point and shoot fundus photography of the eye. The auto-focus macro capability of existing consumer cameras is adapted to photograph the retina over an extended diopter range, eliminating the need for manual diopter focus adjustment. The thru-the-lens (TTL) auto-exposure flash capability of existing consumer cameras is adapted to photograph the retina with automatic flash exposure eliminating the need for manual flash adjustment. The consumer camera imaging sensor and flash are modified to allow the camera sensor to perform both non-mydriatic focusing of the retina using infrared illumination and standard color flash photography of the retina without the need for additional imaging sensors or mechanical filters. These modifications and integration of existing consumer cameras for fundus photography of the eye significantly improve ease of manufacture and usability.

RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 15/174,431, filed Jun. 6, 2016, entitled “Hand-Held Portable FundusCamera for Screening Photography”, which is a continuation of U.S.patent application Ser. No. 13/394,055, filed May 21, 2012, entitled“Hand-Held Portable Fundus Camera for Screening Photography”, which is aU.S. National Stage filing under 35 U.S.C. 371 from International PatentSer. No. PCT/US2010/047909, filed Sep. 3, 2010 and published on Mar. 10,2011 as WO 2011/029064 A1, entitled “Hand-Held Portable Fundus Camerafor Screening Photography”, which claims priority from U.S. ProvisionalApplication Ser. No. 61/240,027, filed Sep. 4, 2009, entitled “Hand-HeldPortable Fundus Camera and Related Method thereof”, and U.S. ProvisionalApplication Ser. No. 61/372,270, filed Aug. 10, 2010, entitled“Hand-Held Portable Fundus Camera and Related Method thereof”, each ofwhich is hereby incorporated by reference herein in its entirety and thebenefit of priority of each of which is hereby presently claimed.

FIELD OF THE INVENTION

The present invention relates to a fundus camera for photographing thefundus of an eye and more particularly to a portable fundus camera inwhich additional optics and illumination are fully integrated with anexisting consumer camera device to enable the consumer camera device toperform point and shoot photography the retina. The enhancement ofcapabilities of the existing consumer camera device enable a funduscamera with overall lower complexity, higher degree of integration,improved ease of manufacturing, automatic focusing and automatic imageexposure for retina screening photography as compared to existing andproposed fundus camera devices.

BACKGROUND OF THE INVENTION

Diabetic Retinopathy (DR) is an eye disease affecting millions ofpatients with type I and type II diabetes. 45% of Americans diagnosedwith diabetes have some form of DR, and nearly all patients who havetype I diabetes for more than 20 years will show signs of DR. In the US,DR is responsible for almost 8% of legal blindness and is the leadingcause of new cases of blindness in adults of 20-74 years of age. Inaddition, the presence of DR is growing at a dramatic rate in developingcountries as the number of type II diabetics increases. In India,diabetic retinopathy has jumped from 17^(th) to the sixth leading causeof blindness within twenty years. Similar increases can be seenworldwide and has become a key concern for the World HealthOrganization.

With close monitoring and annual eye exams, diabetic retinopathy can bediagnosed and successfully treated. According to the American Academy ofOphthalmology (AAO), 95 percent of diabetics with DR can avoid visionloss if treated on time. For this reason, a yearly dilated screeningexam is currently recommended by the AAO for all diabetic patients.Traditionally dilated screening exams have required referral to eye carespecialists because patient's primary care facilities lack the necessarytools and staff to properly diagnose DR. Due to the inconvenience andextra cost associated with seeing a specialist, patients often fail tofollow up on their referral.

Over the last two decades, multiple attempts have been made to addressthese barriers to screening involving placement of a camera for retinaphotography within the primary care physician's office. These effortshave largely been hampered by difficult to use and expensive retinaldiagnostic devices costing upward of $50,000. Retina camera cost hasremained high due to the inherently demanding optical and illuminationdesign that requires complex manufacturing processes. Usability and costof the devices have similarly been limited by the need to implement acustom image recording device to accurately record images formed bythese complex optical designs. These custom image recording devicesusually require multiple image sensors and image display units forinitial image alignment/focusing and actual final image acquisition.Further, they often require manual control of focusing, image exposure,and white balance, to achieve acceptable final image acquisition,limiting their use to skilled practitioners of ophthalmic photography.

A standard consumer camera device such as a “point and shoot” or DSLRcamera does not have an inherent capability to perform fundusphotography given the complex optics and illumination required to forman image of the retina. In most existing fundus cameras, the deviceforms a donut of illumination measuring approximately 3 mm to 7 mm thatis focused on the patient's eye. This donut of light is formed by thefundus camera itself through a series of optics and built inillumination source. Alternatively, off axis non-donut illumination canbe used and is the basis of indirect ophthalmoscopy. This approach isnot commonly employed commercially as photographic quality is impactednegatively by this technique, in particular with respect to evenness ofthe field illumination as compared to donut illumination. Condensinglenses are required to form an image of the retina that is created bythe reflection of light off the back of the eye in response to the donutillumination. Most cameras then employ a separate optics stage to focusthe retinal image produced by the condensing lens onto a CCD or CMOSimage sensor either built into or externally attached to the device(e.g., a consumer camera device digital camera back which consists ofthe DSLR body with image sensor alone without the detachable front DSLRcamera lens on it). Even when a digital camera back is used, thisapproach has significant limitations in that auto-focus, auto-exposure,auto-white balance capabilities of the consumer camera device are nolonger available. Finally, non-mydriatic fundus photography, in whichthe patient does not require prior pharmacologic dilation, is commonlyused in screening photography and relies on infrared wavelength light tocompose and focus the image of the retina before final image capture. Toachieve proper color balance on the final image recorded on the camera,many devices split off the infrared wavelengths to a second infraredsensitive image sensor to be used for focusing, and send the visiblewavelength light to a separate visible light sensitive image sensor forfinal image capture. When a consumer camera device digital camera backis used for final image capture, this split off is required as consumercamera devices are sensitive only to visible light wavelengths.

Conventional fundus cameras require manual control of image exposure andflash power resulting in the need for multiple photos to obtain acorrectly exposed image.

Many conventional fundus cameras are heavy and large and requireexternal power and observation monitors and other systems, which add totheir size and limit their mobility. True size portability and batterybased power is critical for establishing mobile screening clinics whereindependent traveling clinicians, for example, must be able to easilyset up low-cost screening programs in areas with little access toelectricity and other medical equipment.

The complexity of conventional systems requires extensive training andthe need for specialists to obtain adequate images of the fundus. Thislimits the ability to deploy fundus cameras to a large number ofclinics, especially primary care clinics, and therefore prevents thosewho may need treatment from getting screened for retinopathy.Furthermore, many conventional fundus cameras are expensive and cannotbe produced at a low cost. This also prevents deployment of thediagnostic imaging equipment necessary to screen many patients.

For non-mydriatic diagnostics, existing fundus cameras generally requirethe use of two separate systems for observation and photography of thefundus. In these systems an infrared imaging sensor is needed forobservation and another imaging sensor is needed for visible lightphotography. This is particularly true when a consumer camera devicebody is used to record images as these devices are only sensitive tovisible wavelengths of light. This has the disadvantage of adding cost,complexity in manufacture, and size to the overall fundus camera designand prevents these cameras from achieving true mobility and portabilityat a low cost.

CCD and CMOS sensors used in consumer camera devices are inherentlysensitive to infrared wavelengths and an infrared cutoff filter is usedto prevent infrared wavelengths from reaching the image sensor of theconsumer camera device. If this filter were not present, significantimage distortion from infrared wavelengths would be present in therecorded image. Some consumer camera devices have used a single sensorto record both infrared and visible wavelengths of light by using amechanical filter that is automatically rotated into position andfilters out infrared wavelengths when taking a normal visible spectrumphoto. This is an unnecessarily complex and difficult to manufacturemechanism and this design is no longer in commercial production.

While conventional approaches discussed above may provide certaincapabilities, none of their uses achieve true portability, in aninexpensive, pragmatic form so as to solve problems as described above.

SUMMARY OF INVENTION

An aspect of an embodiment of the present invention is to overcome thevarious problems described above, but not limited thereto, and thereforeprovide a new photographic device available for screening DiabeticRetinopathy and other retinal pathologies in primary care facilities andtertiary care clinics.

Effective screening strategies for tele-ophthalmology detection of DRrequire a low cost, low complexity, high manufacturability, highscalability, highly portable, easy to use fundus camera that can bedistributed across a wide network with efficient transmission ofcaptured images for review. In the present invention we describe adevice that accomplishes each of these goals. Ease of manufacturing isachieved in part by using off the shelf components, in particular aconsumer camera device that is fully integrated with the optics andillumination that enable it to take fundus photographs. In addition,ease of manufacturing is achieved by reducing the number of elementsrequired in the complex optic and illumination path to enable fundusphotography. The optical and illumination design is optimized to use offthe shelf inexpensive commonly available components.

In an embodiment of the present invention, ease of use is achieved inpart by taking advantage of the built-in inherent capabilities of theconsumer camera device, in particular auto-focus and auto-exposure.Auto-focus is achieved by retaining the usual front lens on the consumercamera device and thru use of a combination of macro extension rings andmacro optics, enhancing the normal macro capabilities of the consumercamera device to focus on the retina image formed by the frontcondensing lens of the fundus camera. For a DSLR type consumer cameradevice, manufacturing is further enhanced by incorporating the frontlens into the fundus camera housing of the fundus camera itself to serveas the point of integration and attachment to the consumer camera deviceDSLR body. Precise modification of the focal distance of the front lenson the consumer camera device allows the consumer camera device to focuson the retina image formed by the front condensing lens over a widerange of patient refractions. In contrast, most existing fundus camerasrequire either manual focus by the user of the fundus camera, or complexoptical mechanisms to achieve auto-focus.

An aspect of an embodiment of the present invention providesauto-exposure that may be achieved by taking advantage of built-inthrough-the-lens (TTL) exposure metering systems inherent in manyconsumer digital cameras and using a TTL enabled external flash.Conventional fundus cameras require manual control of image exposure andflash power resulting in the need for multiple photos to obtain acorrectly exposed image. Whereas, regarding an aspect of an embodimentof the present invention, by incorporating the external TTL enabledflash into the fundus camera, the consumer camera device integrated intothe fundus camera can correctly set image exposure. This is achieved byemission of lower power pre-flash by the external flash to determine theappropriate full flash exposure for the photograph. The timing betweenpre-flash and actual flash used to expose the retina is such that thepupil is unable to constrict during the interval between pre-flash andfull flash. Thus, the pre-flash does not constrict the pupil such thatnon-mydriatic (undilated pupil) photography is possible even with a TTLbased exposure system.

Many conventional fundus cameras are heavy and large and requireexternal power and observation monitors and other systems, which add totheir size and limit their mobility. True size portability and batterybased power is critical for establishing mobile clinics whereindependent traveling clinicians, or example, must be able to easily setup low-cost screening programs in areas with little access toelectricity and other medical equipment. An aspect of an embodiment ofthe present invention provides a battery based power that can beachieved by using low power LED lights in the fundus camera for focusingillumination and powering both the consumer camera device and externalflash using their built in batteries. Portability is achieved byincorporating the consumer camera device front lens into the cameradesign, and simplifying the optical design, such that the additionalrequired optical illumination and focusing elements can be contained ina housing of comparable size to a large DSLR telephoto zoom lens

An aspect of an embodiment of the present invention provides thecapability to improve cost and manufacturability when using a consumercamera device body for image recording. This can be achieved at least inpart by modifying the consumer camera device so that its image sensor issensitive to infrared wavelengths. This is accomplished by removal ofthe infrared cutoff filter that is present in each consumer cameradevice over the image sensor of the consumer camera device and replacingit with a clear filter of appropriate size and thickness that will passboth infrared and visible wavelengths to the image sensor. Specificationof the optical properties of the clear filter are critical to retaincorrect exposure and auto-focus capabilities of the consumer cameradevice.

CCD and CMOS sensors used in consumer camera devices are inherentlysensitive to infrared wavelengths and the infrared cutoff filter is usedto prevent infrared wavelengths from reaching the image sensor of theconsumer camera device. If this filter were not present, significantimage distortion from infrared wavelengths would be present in therecorded image. Some consumer camera devices have used a single sensorto record both infrared and visible wavelengths of light by using amechanical filter that is automatically rotated into position andfilters out infrared wavelengths when taking a normal visible spectrumphoto. This is an unnecessarily complex and difficult to manufacturemechanism and this design is no longer in commercial production.However, pertaining to an aspect of an embodiment of the presentinvention, to obtain correctly exposed color images of the retinawithout infrared distortion it is possible to place multiple infraredfilters in front of the flash of the fundus camera so that only visiblewavelengths of light produced by the flash are transmitted to the retinaand reflected to the image sensor of the consumer camera device. Thisallows use of an infrared light source that the image sensor of theconsumer camera device is sensitive to for focusing the retinal image ofthe eye, and then a visible light only flash to record the final colorimage on the image sensor of the consumer camera device. This highlymanufacturable device of this embodiment requires no additionalmechanical devices to perform this function, which simplifiesreliability, lowers device complexity and ultimately lowers device cost.In fact, it is not even necessary to add timing circuitry to turn theinfrared focusing light source off during flash photography as the lightintensity produced by the flash so exceeds the light intensity of theinfrared focusing light that effectively infrared wavelengths of lightdo not significantly contribute to the final recorded image. This againsimplifies device complexity over existing non-mydriatic cameras.

An aspect of an embodiment of the present invention may be achieved bymodifying an inexpensive consumer digital camera into a stand-alonemydriatic and non-mydriatic portable fundus camera which is capable ofcomposing and acquiring images of the fundus, storing those images, andtransmitting them over a wired or wireless telemedicine network toenable efficient and cost-effective retinal screening. Briefly, thetransformation of a consumer digital camera to fundus camera involvesseveral novel modifications including, but not limited to, attaching amodular optical and illumination system held in a housing to the frontlens of the consumer digital camera wherein the modular system is ableto produce and relay an image of the fundus to the image sensor of thecamera such that the auto-focus capabilities of the camera are retained,attaching an external through-the-lens (TTL) metering enabled flash tothe camera to allow for auto-exposure, and finally modification of thecamera's CCD or CMOS image sensor to allow for non-dilated fundusexaminations. Through the modifications, an inexpensive consumer digitalcamera becomes capable of producing images of the fundus comparable toexisting commercial fundus cameras which cost upward of $50,000. Thevarious embodiments of the present invention described below, forexample, have a total estimated cost of perhaps under $1,000, andtherefore present a significant leap forward in both the realm ofmanufacturability and accessibility to customers within the existingcommercial fundus camera market.

It should be appreciated that rather than modifying an existing digitalcamera or device, the original manufacturing of the desired or requireddevice or system and related components may be implemented as well, andshall be employed within the context of the invention.

An embodiment of the present invention portable fundus camera mayinclude a consumer digital camera tethered to a modular attachment whichprovides all necessary optical and illumination components to produce animage of the fundus. The attachment interfaces with the camera in such away that both auto-focus and auto-exposure capabilities inherent in theconsumer camera are retained. By basing the design around a consumerdigital camera, the present technology leverages recent advancements inconsumer camera technology such as, but not limited thereto, theintroduction of LiveView LCD screens, advanced TTL metering systems,image stabilization, in-camera noise reduction algorithms, etc. Camerason the market currently suitable for the present invention include, butare not limited thereto, advanced ‘prosumer’ point and shoot cameras(e.g., Canon G11, Nikon P6000, Panasonic LX5) in addition to recentlyreleased micro 4/3rds cameras (e.g., Panasonic G2) which featureincreased image sensor size and an interchangeable lens design. In anembodiment, the portable fundus camera may be designed for the micro4/3rds cameras, thereby incorporating a non-changing interchangeablelens and therefore able to be easily upgraded as camera technologyfurther develops (e.g. subsequently released cameras within the samemake/model). This enables the portable fundus camera to be easilyupgraded to improve image quality as digital sensor technology advances.

An aspect of an embodiment of the present invention provides forinterfacing the portable fundus camera with a consumer digital cameraand consequently provides the advantage of ease of operation bynon-trained personnel. Operation of the novel fundus camera as describedstrives for a “point & shoot” approach to fundus photography. The easeof operation is an aspect of the present invention previously neverachieved by fundus cameras on the market today. By retaining the builtin camera shooting modes of the consumer digital camera, users of anembodiment of the present invention portable fundus camera can take apicture of a patient's retina in much the same way he or she can takethe picture of an everyday object with a standard unmodified consumercamera. In brief, a user of an embodiment of the present inventioncamera would turn on the digital camera, turn on the illumination switchon the housing and aim the camera at a patient's eye. Image compositionis achieved through the built-in LCD screen on the camera, and aproperly exposed image is produced by a TTL-metered external flash whenthe shutter is pressed. Review of the images can be performed directlyon the camera. Because operation of an embodiment of the presentinvention fundus camera does not differ markedly from operation of apoint & shoot camera, non-trained medical personnel such as nurses orfield technicians can quickly learn how to take appropriate images ofthe fundus without extensive and expensive training, furtherfacilitating the feasibility of success of a wide-spread diabeticretinopathy screening program. In addition, being based on a digitalcamera limits an exemplary embodiment of the present invention funduscamera may have a size of approximately 5″ (D)×10″ (L)×5″ (H). Thesedimensions comprise a self-powered, stand-alone fundus camera capable ofacquiring, storing and transmitting images of the fundus, a feature thatno other fundus camera on the market has been able to previouslyachieve. Size and portability are important for being able to move fromexam room to exam room, and is a critical aspect for diagnosing patientswith reduced mobility or infants.

Another advantage of designing an embodiment of the present inventionfundus camera around a consumer digital camera is ease of manufacturing.By leveraging the low cost of mass-produced consumer cameras, desirablefunctions of fundus cameras such as LCD screen technology, auto-focus,auto-exposure, image stabilization, and last but not leasthigh-resolution, low noise image sensors can be obtained at a fractionof the cost of an OEM design. This aspect of an embodiment of thepresent invention enables the camera to retain (and add to) manyfeatures of high-end fundus cameras at the fraction of the cost, therebysignificantly reducing the price of the overall fundus camera to pricepoints less than 1/20^(th) of the cost of existing tabletop funduscameras. The cost-conscious fundus camera design of an embodiment wouldenable a large number of primary care practitioners both in the US andabroad to establish affordable screening programs for common retinaldiseases.

The design of the modular attachment of an embodiment of the presentinvention, which consists of all of the optical and electrical elementsnecessary to produce an image of the fundus for the consumer camera toimage, largely consists of low cost commercially available optical andLED circuit components. Non-limiting components comprised in the modularattachment include, but are not limited to: a front objective lens forimaging the retina of with a power approximately 22 D withanti-reflection coatings, a beamsplitter, a pair of linear polarizers, alight gathering converging lens, a mirror, an annular image mask, aninfrared cold mirror, a xenon flash tube and reflector assembly, heatabsorbing glass, an infrared cut-off filter, a diffuser, infrared and/orvisible wavelength high power LEDs and circuitry to switch on and offand power the LEDs. Non-limiting features include a shared light pathbetween the image produced of the fundus and the illumination of theaforementioned fundus, a shared light path for both infrared and visibleillumination, and the ability for the aforementioned components to beintegrated with a consumer digital camera for user control, focusing,digital display, and digital storing of the image of the fundus. In anembodiment, for example, emphasis may be placed on designing the modularattachment to be small, yet ergonomic and maintain a total parts cost ofless than $300.

In order for practicing ophthalmologists to diagnose retinal disease, itis necessary for them to work with high-resolution, large image field,and artifact free photographs of the fundus. These aspects are criticalin identifying micro aneurysms and dot blot hemorrhages common topatients with developing diabetic retinopathy. An embodiment of thepresent invention portable fundus camera is capable of taking imageswhich meet these quality requirements by taking advantage of newlow-noise image sensors, as well as the macro focusing ability of theconsumer digital camera. This macro ability is achieved by a novelintegration and placement of the camera front lens, macro lenses, andthe front objective lens, thereby allowing the fundus image to fill theimage sensor and thus capture details ordinarily lost under standardnon-macro imaging. An artifact and reflection free image of the retinais produced by a method of illumination present in many existingcommercial fundus cameras in which an annular ring of light is focusedon the cornea by means of a front objective lens. As this focused ringof light travels through anatomical elements of the eye (cornea,anterior cavity, lens and posterior cavity), it expands to fill theretina. The fully illuminated image retina is then relayed through thefront objective lens to produce a retinal field of approximately 50°,which is subsequently relayed to the consumer camera's front lens andfinally to the image sensor of the camera. In addition to using theaforementioned annular illumination technique, an embodiment of thepresent invention portable fundus camera introduces a novel applicationof cross-polarization using a pair of low-cost linear film polarizers inorder to further reduce corneal haze and reflection artifacts from thefront lens.

The success of a wide-spread retinal disease (e.g. Diabetic Retinopathy)screening program is largely dependent upon the speed and efficiency ofphotography patient's eyes. Typically, patient's eyes have to be dilatedin order to maintain a sufficiently large pupil diameter to allow forfundus photography. Commercial dilating drops often take upward of 30minutes to take effect and significantly increase the time required tomove patients in and out of the clinic. Therefore, an embodiment of theportable fundus camera should be capable of non-mydriatic imaging, or inother words, do not require the patient to be dilated. Previously, thishas been accomplished by installing a separate infrared sensitive CCD orCMOS sensor and illuminating the patient with infrared light. Becausethe human eye is not sensitive to infrared wavelengths, the patient'spupil can maintain a sufficiently large diameter in a low-lit room toallow for unobstructed fundus photography. An aspect of an embodiment ofthe present invention follows a similar technique for enablingnon-mydriatic imaging, but incorporates a novel aspect in that a singlesensor is used for both infrared imaging and visible light imaging forcapturing the final fundus image. In brief, this aspect of the designinvolves removal of the infrared filter placed in front of all consumerdigital cameras and filtering the infrared light from the incoming finalimage acquisition illumination source, thereby allowing non-mydriaticinfrared image composition while maintaining a properly exposed andcolor-balanced final image of the fundus.

Associated with the aforementioned aspects, another aspect of anembodiment is to serve as a basis for a telemedicine-based screeningprogram. This program may include a secure online database which will beautomatically managed. Clinicians will be able to upload the imagestaken from our camera into this database. On the receiving end of thissystem will be a team of specialists who can then virtually examine eachpatient and determine if there are signs of Diabetic Retinopathy orother retinal diseases. This method and related system will enable highthroughput of patient diagnostic information and will be a majorimprovement over the current practice of referring patients tospecialists. Patients at risk for Diabetic Retinopathy will be able tobe screened at the convenience of their own primary care clinic. Beingless reliant on expensive retinal imaging equipment, the new screeningmethods will also be able to be deployed in developing countries wherethere are currently limited diagnosing centers or certified physicians.As such, the proposed portable fundus camera has the potential to savethe vision of millions of at-risk patients.

An aspect of an embodiment of the present invention, a hand-heldportable fundus camera, as embodied and broadly described herein,comprises a module optical system which is capable of being integratedwith a portable independent image recording device for photographing thefundus of an eye, the independent image recording device comprises arecording device observation optical system and a recording devicephotography system, the recording device observation optical system andthe recording device photography optical system sharing a common opticalpath, and the module optical system comprising a housing, a moduleoptical path which is common to the recording device observation opticalsystem and recording device photography system when the independentimage recording device is integrated with the module optical system, afront objective lens, a module illumination optical system where anillumination optical path of the module illumination optical system ispartially shared with the module imaging optical path and theillumination optical path is coaxial with the module imaging opticalpath by a beam splitter wherein the module illumination optical path isreflected of the beam splitter whereby the illumination optical path isdirected through the front objective lens, and coupling means forcoupling the module optical system with the independent image recordingdevice.

In another aspect of an embodiment of the present invention, the moduleillumination optical system further comprises an observation lightssource, a photographing light source, and a hot mirror filter whereinthe observation light source and the photographing light source sharethe illumination optical path through the means of the hot mirror filterwhich is disposed coaxial to the illumination optical path, the hotmirror filter blocking infrared light being emitted from thephotographing light source and redirecting light from the observationlight source into the illumination optical path.

In another aspect of an embodiment of the present invention, a hand-heldportable fundus camera comprises an illumination optical system forilluminating the fundus of an eye, an observation optical system forobserving the fundus, and a photography optical system for photographingan image of the fundus, the camera comprising a front objective lens, anobservation light source, a photographing light source, a beam splitter,and a CCD imaging element wherein the observation optical system and thephotographing optical system share a common optical path, wherein theobservation optical system and photographing optical system share theCCD imaging element, wherein the common optical path is furtherpartially shared by a illumination optical path of the illuminationoptical system wherein the beam splitter is disposed in the commonoptical path coaxial to the illumination optical path whereby theillumination optical path is reflected off the beam splitter anddirected through the front objective lens, and wherein the illuminationoptical system delivers only infrared light to the CCD imaging elementwhen observing the fundus by the observation optical system and deliversonly visible light to the CCD imaging element when photographing thefundus through the photographing optical system.

In another aspect of an embodiment of the present invention, a hand-heldportable fundus camera comprises an illumination optical system forilluminating the fundus of an eye, an observation optical system forobserving the fundus, and a photography optical system for photographingan image of the fundus, and the camera further comprising a frontobjective lens, and a beam splitter, wherein the observation opticalsystem and photographing optical system share a common optical path, andwherein the common optical path is further partially shared by aillumination optical path of the illumination optical system through themeans of the beam splitter whereby the illumination optical path isreflected off the beam splitter and directed through the front objectivelens.

An aspect of an embodiment of the present invention provides a hand-heldportable fundus camera system and related method of use and manufacture.The hand held fundus camera system (and related method of use andmanufacture) may comprise: a module optical system capable of beingintegrated with a consumer camera device for auto focus photography bythe consumer camera device of the fundus of an eye. The module opticalsystem may comprise: a composing image acquisition illuminationobservation source (e.g., photographing light source); a final imageacquisition illumination source (e.g. observation light source); anoptical separator and transmitting means (e.g., IR filter, heatabsorbing glass, cold mirror/beam splitter or the like) for separatingand transmitting the composing image acquisition observationillumination source and the final image acquisition illumination sourceto an image mask, of which is relayed to the retina of the fundusthrough the use of a redirecting mirror, a beam splitter and a frontobjective lens. The image mask may be configured to provide light thatilluminates the retina to output an image that is relayed through theobjective lens and captured by the consumer camera to provide an imageof the retina. Also included is a module interface system (e.g. macrolenses, physical couplings, macro extension ring) to integrate themodule optical system with the consumer camera device. It should beappreciated that the module interface system enhances the macro focusingcapability of the consumer camera device to enable auto-focusphotography by the consumer camera device of the fundus image producedby the front objective lens.

An aspect of an embodiment of the present invention provides a hand-heldportable fundus camera system and related method of use and manufacture.The hand-held portable fundus camera system (and related method of useand manufacture) may comprise a module optical system capable of beingintegrated with a consumer camera device for photographing the fundus ofan eye. The module optical system may comprise: a composing imageacquisition illumination observation source (e.g., photographing lightsource); a final image acquisition illumination source (e.g. observationlight source); and an optical separator and transmitting means (e.g., IRfilter, heat absorbing glass, cold mirror/beam splitter) for separatingand transmitting the composing image acquisition observationillumination source and the final image acquisition illumination sourceto an image mask the image mask, of which is relayed to the retina ofthe fundus through the use of a redirecting mirror, a beam splitter anda front converging lens. The module optical system may further comprise:the image mask being configured to provide light that illuminates theretina to output an image that is relayed through the front objectivelens and captured by the consumer camera device to provide an image ofthe retina. The consumer camera device may comprise a consumer point andshoot or digital single lens reflex system (DSLR) module for automatedimage capture and review. The consumer camera device may furthercomprise: an external flash device; a hot shoe adapter in communicationwith the external flash device, wherein the captured image beingprovided by the consumer camera device being in communication with thefinal image acquisition illumination source. Moreover, the capturedimage may be properly exposed by the consumer camera device being incommunication with the final image acquisition illumination source,wherein the external flash device comprises through the lens (TTL)metering to allow the consumer camera device to provide properly exposedimages of the retina.

An aspect of an embodiment of the present invention provides a hand-heldportable fundus camera system and related method of use and manufacture.The hand-held portable fundus camera system (and related method of useand manufacture) may comprise a module optical system capable of beingintegrated with a consumer camera device for photographing the fundus ofan eye using infrared illumination for focusing of the image by theconsumer camera device. The module optical system may comprise: acomposing image acquisition illumination observation source (e.g., old:photographing light source), wherein the wavelength of the imageacquisition illumination source is infrared; a final image acquisitionillumination source (e.g., xenon flash tube); and an optical separatorand transmitting means (e.g., IR filter, heat absorbing glass, coldmirror/beam splitter) for separating and transmitting the composingimage acquisition illumination observation source and the final imageacquisition illumination source to an image mask, of which is relayed tothe retina of the fundus through the use of a redirecting mirror, a beamsplitter and a front objective lens. The module optical system mayfurther comprise the image mask configured to provide light thatilluminates the retina to output an image that is relayed through thefront objective lens and captured by the consumer camera to provide animage of the retina. The optical separator and transmitting means mayfurther comprise at least one or more of ‘a’, ‘b’, or ‘c’. Whereby ‘a’,‘b’, or ‘c’ may include the following: a) separating and transmittingthe composing image acquisition illumination observation source that isof infrared wavelengths and the final image acquisition illuminationsource that is of visible wavelengths; b) separating and transmittingthe composing image acquisition illumination observation source that isof visible and infrared wavelengths and the final image acquisitionobservation illumination source that is of visible and infraredwavelengths; c) separating and transmitting the composing imageacquisition illumination observation source that is of visiblewavelengths and the final image acquisition illumination source that isof infrared wavelengths. The fundus camera may further comprises of atleast one of: an infrared cutoff filter optically disposed between thefinal image acquisition illumination source and the optical separatorand transmitting means; or an infrared cutoff filter optically disposedbetween the composing image acquisition illumination source and theoptical separator and transmitting means. And wherein the consumercamera device may comprise a consumer point and shoot or digital singlelens reflex system module for automated image capture and review,whereby an infrared filter has been removed or bypassed from theconsumer point and shoot or the digital single lens reflex system moduleand replaced with a full spectrum filter. The consumer camera device mayfurther comprises: an external flash device; a hot shoe adapter incommunication with the external flash device, whereby the captured imagebeing provided by the consumer camera device being in communication withthe final image acquisition illumination source; and wherein thecaptured image being properly exposed by the consumer camera devicebeing in communication with the final image acquisition illuminationsource; and wherein the external flash device comprises through the lens(TTL) metering to allow the consumer camera device to provide properlyexposed images of the retina.

An aspect of an embodiment of the present invention relates to themodification and integration of an existing consumer digital camera, forexample, with an optical imaging module to enable point and shoot fundusphotography of the eye. The auto-focus macro capability of existingconsumer cameras is adapted to photograph the retina over an extendeddiopter range, eliminating the need for manual diopter focus adjustment.The thru-the-lens (TTL) auto-exposure flash capability of existingconsumer cameras is adapted to photograph the retina with automaticflash exposure eliminating the need for manual flash adjustment. Theconsumer camera imaging sensor and flash are modified to allow thecamera sensor to perform both non-mydriatic focusing of the retina usinginfrared illumination and standard color flash photography of the retinawithout the need for additional imaging sensors or mechanical filters.These modifications and integration of existing consumer cameras forfundus photography of the eye significantly improve ease of manufactureand usability over existing fundus cameras.

An aspect of an embodiment of the present invention provides hand-heldportable fundus camera system comprising a module optical system capableof being integrated with a consumer camera device for photographing thefundus of an eye of a subject using infrared illumination for focusingof the image by the consumer camera device.

Available methods for the fabrication of any and all of the embodiment,systems, devices, compositions, materials, computer program logic,computer processing, and components discussed throughout this disclosureare also considered part of the present invention. A method ofmanufacturing of any and all of the embodiments, systems, devices,compositions, materials, computer program logic, computer processing,and components discussed throughout this disclosure may be employedwithin the context of the invention.

Additional aspects and advantages of various embodiments of theinvention will be set forth in part in the description which follows andin part will be obvious from the description, or may be learned bypractice of various embodiments of the invention. The aspects andadvantages of various embodiments of the invention may be realized orattained by means of the instrumentalities and combinations particularlypointed out in the appended claims.

Aspects of various embodiments of the invention itself, together withfurther objects and attendant advantages, will best be understood byreference to the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the instant specification, illustrate several aspects and embodimentsof the present invention and, together with the description herein,serve to explain the principles of aspects of various embodiments theinvention. The drawings are provided only for the purpose ofillustrating select embodiments of the invention and are not to beconstrued as limiting the invention.

FIG. 1A provides a schematic block diagram of an embodiment of thesystem for capturing and storing images of the fundus.

FIG. 1B provides a schematic block diagram of an embodiment of thesystem for capturing images and including communication between thesystem and local and remote locations.

FIG. 2A provides a schematic view showing a structure of a moduleoptical system to be connected with an independent image recordingdevice of an embodiment.

FIG. 2B provides a schematic view of the module imaging optical path ofan embodiment.

FIG. 2C provides a schematic view of the illumination optical path of anembodiment.

FIG. 3 provides a perspective schematic view of an embodiment showing anexternal view of a module optical system housing and a view of couplingsystems and connection/communication interfaces between a module opticalsystem and an independent image recording device.

FIG. 4 provides a schematic block diagram illustrating an embodiment ofthe basic illumination circuitry required for synchronizing the use ofthe independent image recording device with triggering the photographingillumination in the module optical system.

FIG. 5A provides a schematic view of various components for mydriatic ornon-mydriatic imaging of the portable fundus camera as described.

FIG. 5B provides an exploded view of a depiction of the imaging sensorof the consumer digital camera and related of the portable fundus cameraas described.

FIGS. 6 and 7 provide 2D and 3D assembly instructions of an embodimentof the portable fundus camera, respectively.

FIG. 8 provides an external schematic view of an embodiment of theportable fundus camera

FIG. 9 provides a schematic illustration of an annular ring of lightused to illuminate the retina

FIG. 10 schematically illustrates a means of polarization to eliminatelens back reflections and corneal haze.

FIG. 11A and FIG. 11B illustrate the effect of the digital subtractionof spectral content of back light reflections practicing an embodimentof the present invention. FIG. 11A provides a recorded retinal imageprior to digital subtraction of back light reflections. FIG. 11Bprovides a recorded retinal image after digital subtraction of backlight reflection.

FIG. 12A and FIG. 12B illustrate the effect of the digital subtractionof back light reflections by combining multiple images practicing anembodiment of the present invention. Retinal image no. 1 (FIG. 12A) iscombined with retinal image no. 2 (FIG. 12B) to provide a combined image(FIG. 12C) without back light reflections.

FIG. 13A and FIG. 13B illustrate the effect of digital enhancement ofcentral white balance practicing an embodiment of the present invention.FIG. 13A provides a recorded retinal image prior to digital enhancementof central white balance. FIG. 13B provides a recorded retinal imageafter digital enhancement of central white balance practicing anembodiment of the present invention.

FIG. 14A and FIG. 14B illustrate practicing an embodiment of the presentinvention. FIG. 14A illustrates an embodiment using a Canon G10 consumercamera device. FIG. 14B illustrates practicing a mydriatic embodimentusing the Canon G10 consumer camera device on a human eye. FIG. 14Cillustrates practicing a non-mydriatic embodiment using the Canon G10consumer camera device on a human eye.

FIG. 15A, FIG. 15B, and FIG. 15C illustrate practicing an embodiment ofthe present invention. FIG. 15A and FIG. 15B illustrate an embodimentusing a Panasonic Lumix G2 consumer camera device. FIG. 15C illustratesthe resultant fundus image practicing a mydriatic embodiment.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is provided below with referenceto the accompanying drawings. FIG. 1A provides a block diagram of theembodiment of the present invention which indicates the basic componentparts of the system for photographing the fundus and storing images. Thefundus camera may consist of a module optical system 2 which providesthe optical and illumination means necessary to produce and image theretina. This module optical system 2 may be attached to an independentimage recording device 1, which provides the means of previewing thefundus photographs, photographing the fundus, and storing images. In anembodiment, but not limited thereto, the independent image recordingdevice 1 consists of a consumer digital camera or device. Theintegration of the module optical system 2 and the independent imagerecording device 1 mydriatic and non-mydriatic portable fundus camerawhich is capable of composing and acquiring images of the fundus,storing those images, and transmitting them over a wired or wirelesstelemedicine network to enable efficient and cost-effective retinalscreening. In an embodiment, these photographs are stored on theindependent image recording device until they can be transferred via anetwork transfer system 18 to an archiving system 19 for laterdiagnostics. The network transfer system 18 may transfer the photographson the independent image recording device 1 either through wired datatransfer means or via wireless data transfer means.

FIG. 1B provides a block diagram of how images stored on the independentimage recording device 1 may be communicated through a transmissionmodule 25 to either a local 26 and/or remote 27 location. It should beappreciated that the local and/or remote location may include, but arenot limited thereto, a user, a processor, a display, a database, anarchive, or any combination thereof. This may enable specialists tocomplete diagnostics using the images at local or remote locations andenable telemedicine practices to be used. In using telemedicinepractices, the images may be transmitted through the transmission module25 to a remote location 27 where they are later reviewed byophthalmologists or other trained specialists. If the image shows thatthe patient has a disease or defect, the patient may then be referred toa specialist for more testing and treatment. In this situation, imagesof the fundus can be recorded at a primary care clinic without the needfor specialists at the primary care clinic to perform the diagnosis.Reviewing images by specialists at a remote location may allow for moreefficient processing and diagnostics of the recorded images. This mayallow a greater number of patients to be screened for retinal diseasesat a lower overall cost.

FIG. 8 depicts the exterior design of an embodiment of portable funduscamera. It should be noted that the module optical system 2 andperipheral components 61 are placed in such a way that they are indirect communication with the consumer digital camera 1. In anembodiment, the consumer digital camera is one of the ‘point & shoot’variety aimed primarily at advanced ‘prosumer’ camera users in thecurrent personal digital camera market. These cameras include, but arenot limited to, the following features: a low-noise image sensor of theCCD or CMOS variety 53, a hot-shoe adapter 3 to interface with anexternal flash 61, an LCD screen for LiveView 51, a front lens 35 whichcan either be detachable or integrated to the consumer digital camera,the ability to perform auto-focus and macro-focus, the ability toauto-expose images through the use of through-the-lens (TTL) meteringsystems, and the availability of user-set custom modes to assist usersof the portable fundus camera to easily obtain high-resolution, properlyexposed and properly focused images of the fundus. In the presentembodiment, the consumer camera are of the variety easily operated byuntrained personnel and may be, but not limited to, advanced point &shoot cameras such as the Canon G11 and Nikon P6000, or newer mirrorlesscamera systems (Micro 4/3rds) such as the Panasonic G2 or Samsung NEX-1.

FIGS. 2A, 2B, 2C and 5A illustrates an aspect of an embodiment of theoptics and illumination components involved in the module optical system2 which is capable of being integrated with the consumer digital camera1 to transform the consumer camera into a portable fundus camera. Anembodiment of the module optical system 2 may include two centraloptical paths: an imaging optical path and an illumination optical path.The following components may be disposed along these optical paths: afront objective lens 4, a beam splitter 7 which may be disposed alongthe module imaging optical path and is coaxial with the front objectivelens 4, a light trap 6 located above the beam splitter 7, a mirror 8, aconverging lens 9, an image mask 10, a diffuser 10, two linearpolarizers 41 and 43, a cold mirror or beamsplitter 11, heat absorbingglass 31, infrared cut-off 67, a composing image acquisitionillumination observation source 13, a final image acquisitionillumination source 12, a housing 14, and finally a coupling system 15for attaching the module optical system 2 to the independent imagerecording device 1. The module optical system 2 will be described bydescribing the operation of an observation and photography opticalsystem generally disposed along the module imaging optical path and bydescribing an illumination optical system generally disposed along theillumination optical path.

Referring to FIG. 5A, the illumination optical path 24 (not specificallyreferenced in FIG. 5A) includes the retina 5, front objective lens 4,beam splitter 7, second polarizer 43, and macro lens 37. Still referringto FIG. 5A, the module imaging acquisition optical path 23 (notspecifically referenced in FIG. 5A) includes the retina 5, frontobjective lens 4, beam splitter 7, light trap 6, rear converging lens 9,redirecting mirror 8, first polarizer 41, image mask 10, diffuser 17,hot mirror filter 11, composing image acquisition illuminationobservation source 13, IR filter 67, heat absorbing glass 31, and finalimage acquisition illumination source 12.

Optical Path of Illumination

In order to view and photograph the retina, effective illumination ofthe back (fundus) of the eye 5 would generally be required. This may beaccomplished by focusing a bundled donut of light with an outer diameterof roughly the size of a person's pupil, with an inner diameter slightlysmaller than the outer, as depicted as the annular ring 30 in FIG. 9. Anembodiment of the present invention has taken this illumination approachbecause it provides uniform lighting while minimizing cornealreflections.

In an embodiment of the invention, the illumination optical path is atfirst directed parallel to the module imaging optical path. Illuminationlight is provided by a composing image acquisition illuminationobservation source 13 and a final image acquisition illumination source12. The illumination light for observing, previewing, and composing theimage may be provided by the composing light source 13. The composinglight source 13 may be provided by either visible-light LEDs in themydriatic case (dilated), or infrared LEDs in the non-mydriatic case(non-dilated). By using new LED technology, embodiments of the inventionare able to provide high-intensity visible or infrared lighting whilerequiring very little power and very little space. To provide evenhigher intensity light necessary to image the fundus under conditions ofcross-polarization (later described below) a series of multiple LEDs,perhaps three, may be arranged in a circular pattern to providebrighter, more uniform illumination. In order to decrease the risk ofocular hazard to the eye, visible LEDs should be of the warm white type,with perhaps a color temperature of about 2700K in order to decreaseexposure of the retina to wavelengths below about 450 nm. Thesewavelengths, which are closest to the UV range, are extremely hazardousto retinal cells when exposed for extended periods of time. Further, fornon-mydriatic imaging, the LED may have a wavelength between about 700nm and about 1200 nm. In an embodiment, the infrared LED has awavelength of about 750 nm to reduce minor differences in focal rangebetween the composing light source 13 and final image acquisition lightsource 12. The final image acquisition illumination source 13 is usedfor providing adequate light for photography and may be provided by axenon flash bulb. This xenon flash tube is further connected upstream toan external TTL-enabled flash 61, which is further connected to a hotshoe adapter 3 on the consumer camera 1. In an embodiment, both thecomposing image acquisition illumination observation source 13 and finalimage acquisition illumination source 12 are oriented so that theirlight paths are perpendicular to each other and centered on a coldmirror or beamsplitter 11 which is angled at forty-five degrees andexists coaxial with the overall illumination optical path. The coldmirror or beamsplitter 11 redirects the composing image acquisitionillumination observation source 12. More specifically, a cold mirror isused in the non-mydriatic case to redirect only the visible (about 400nm-700 nm) wavelengths to the eye during final image acquisition,whereas an ordinary beamsplitter is used in the mydriatic case. Further,in the non-mydriatic embodiment, heat absorbing glass 31 and an infraredcut-off filter 67 is placed in front of the xenon flash tube to furtherblock infrared light from the final image acquisition illumination. Thecold mirror or beamsplitter 11, infrared cut-off filter 67, and heatabsorbing glass 31 all act in concert to form an optical separator andtransmitting means to provide the necessary composing illumination 13and final image acquisition illumination 12 in order to form a finalimage of the fundus which is free from infrared light contamination. Inan embodiment, it is important to note that this separation is achievedwithout the use of a mechanical mechanism.

After either passing through or being redirected by the cold mirror orbeamsplitter 11, the light from either composing image acquisitionillumination observation source 13 or the final image acquisitionillumination source 12 may now pass through a diffuser 17 whichincreases uniformity of the light. Next, the light passes through animage mask 10 which has a donut cut-out. This will create the bundleddonut of light needed for effective illumination of the eye 5 asdescribed above. The masked image of light may then pass through thefirst of a pair of polarizers 41 in order to create plane-polarizedlight in at a specific angle. In an embodiment, the polarizer is of theinexpensive linear film type. The masked donut of light is thenredirected by a mirror 8 angled at about 45°, and then projected througha small inexpensive converging lens 9. The redirecting mirror 8 isoriented perpendicular to the module imaging optical path. The light maythen be directed toward the eye by being reflected off the beam splitter7. The beam splitter 7 may be about a 50/50 or about 30/70 transmissionand reflectance beam splitter which is coaxial with the module imagingoptical path. Using a beamsplitter with a greaterreflectance-to-transmission ratio results in much less ocular hazard tothe patient's eye, and is therefore an important aspect of an embodimentto be considered. It should also be appreciated that embodiments may usedichroics, such as a triple dichroics in place of the beam splitter toachieve predictable results. Upon being reflected by the beam splitter7, the light along the illumination optical path splits into twoseparate light paths, each with decreased intensities of the originalcorresponding to the specific type of beamsplitter used.

To prevent back reflections off of the light path not illuminating theeye, there may exist a light trap 6 disposed above the beam splitter 7along one of the branches of the illumination optical path which islined with black absorbing felt or an absorbing neutral density filterto effectively capture and trap the light from causing adverse artifactson the final image. The light trap 6 may have walls that are built insuch a way that the majority of light passing through the beam splitter7 is reflected internally within the light trap 6. The light trap 6 isalso disposed at a predetermined distance above the beam splitter 7 soas to reduce the intensity of the light falling on the light absorbingmaterial. The existence of the light trap 6 eliminates the inherent backreflections caused by using a beam splitter 7 on the final image of theretina, and thus improves image quality drastically.

The main branch of the illumination optical path split by the beamsplitter 7, now with only about 30-50% of the original intensity, maynow be directed toward the front objective lens 4 along the moduleoptical imaging path towards the eye 5. In an embodiment, the frontobjective lens 4 may be a standard lens normally used for indirectopthalmoscopy, which is widely available. The front objective lens 4 maynormally be about 50 to 60 mm in diameter and thus provides a largeimage field of about 50 degrees adequate for diagnosing diseases of thevasculature of eye. In addition, these lenses most commonly have workingdistances of close to 50 mm as well, which provides a safe andreasonable distance from the front of the device and the patient's eye5. This feature may be provided to enhance patient comfort during thescreening process as the camera never comes close to being able tophysically contact the patient's eye.

It should be appreciated that at this point, the module imaging opticalpath and illumination optical paths are common and the illuminationoptical path travels through the front objective lens 4. Introducing thebeam splitter 7 at this point allows the working distance (distancebetween the front objective lens and the eye) of the camera to beincreased and results in easier and more convenient operation. This iseasier on the patient and requires less accurate positioning of thecamera in order to acquire adequate images of the fundus. Thus, thosetaking the photographs will require less training and need less time foradequate imaging of the fundus. It should be also be appreciated thatembodiments may use dichroics, such as a triple dichroics in place ofthe beam splitter to achieve predictable results

The introduction of the beam splitter 7 at this point also results in aback reflection on the front objective lens 4. The size and intensity ofthis back reflection is largely a function of the distance between theimage mask 10 and front objective lens 4. Thus, this distance must beoptimized to reduce this reflection as much as possible while stillilluminating the eye effectively. Commercially available indirectophthalmoscopy lenses normally have advanced antireflection coatings aswell which work further to reduce the central reflection. In anembodiment, the front objective lens 4, may be the OI-222 lens made byOcular Instruments. This lens expands the image of the retina, makes itoptically flat, and also has advanced antireflection coatings. In anembodiment, using a commercially available lens such also furthersimplifies the manufacturing process by eliminating the need to designand manufacture a unique objective lens. Methods of eliminating thisback reflection present in an embodiment are through the use of a pairof polarizers 41/43 displaced perpendicularly to each other, or throughimage processing algorithms (for example an image processing module orcomponent 25, both of which are described in detail below.

Once the light has passed through the front objective lens 4, thebundled donut of light is now focused at a fixed distance from the frontobjective lens 4 which also is the location of the front of the eye(cornea). In an embodiment, this distance is roughly 55 mm. Once lightis focused on the front of the eye, it is then passed through thecornea, through the aqueous humor, through the lens of the eye, andfinally through the vitreous humor to reach the retinal surface. In thisprocess, the donut of light disperses and provides a uniform circle oflight without a hole in the middle, thus illuminating the entirety ofthe retinal surface. During this process, the pupil of the eye is notconstricting because the eye is not sensitive to infrared wavelengths inthe non-mydriatic case, or in the mydriatic case the pupil is dilatedand not allowed to constrict.

Imaging Optical System

Once illuminated, the image of the retina is then reflected and passesback through the front objective lens 4, through the beam splitter 7(and also loses another 30-50% of light), and through the secondpolarizer 43, through a set of macro lenses 37 which expand the image,and finally through the front lens 35 to be projected onto the imagesensor 53 of the consumer digital camera 1. In the non-mydriatic case,it is important to note that the infrared cut-off filter 69 inherentlyinstalled on all consumer digital cameras is removed. This enables theconsumer camera to be sensitive to infrared light and is a necessarymodification to allow non0mydriatic imaging. In addition, it should beappreciated that the macro lenses 37 may either be included in themodule optical system 2 or incorporated with the front lens of theconsumer camera 1. In FIG. 2B, the module imaging optical path 23 isshown. As the figure shows, the module imaging optical path is shared byboth the observation optical system and the photographing optical systemwhen integrated with the independent image recording device 1.Therefore, in an embodiment, the optical path is common between theobservation optical system and the photographing optical system andrequires only the photoelectric imaging elements of the independentrecording device 1 for both observation and photography of the fundus.Embodiments of the invention, as described previously through the use ofa discrete optical separator and transmitting means, eliminates the needfor infrared photoelectric imaging elements for observation andvisible-light photoelectric imaging elements for photography.

FIG. 2C illustrates the illumination optical path 24. As describedearlier, the illumination optical path splits into two paths afterreaching the beam splitter 7. One path passes into the light trap 6where it is absorbed and internally reflected. The other branch of theillumination optical path travels along the same path as the moduleimaging optical path as illustrated in FIG. 2A. Accordingly, in anembodiment of the invention, the illumination optical path and moduleimaging path are partially shared by means of the location of the beamsplitter 7. The novel use of common optical paths allows for simplifyingthe overall optical paths and reduces total size. Particularly, thissimplification greatly reduces the number of optical elements requiredfor imaging the fundus thereby allowing a point and shoot consumerdigital camera 1 to be transformed into a stand-alone mydriatic ornon-mydriatic portable fundus camera.

Further, the housing 14 containing the module optical system 2 may beinterfaced with the consumer digital camera 1 by means of a modulecoupling system 15. In an embodiment, the coupling mechanism provides aphysical link between the consumer camera 1 and the housing 14, therebypositioning the two components in such a way that the image of thefundus produced by the front objective lens 4 fills the entirety of theimage sensor 53. In order to accomplish this, a novel clamping mechanismwhich incorporates the camera's front lens 35 into the housing 14 isemployed. This clamping mechanism holds the camera front lens 35 in sucha way that retains the ability of the camera front lens to auto-focusand perform macro-focusing. Further, the camera front lens 35 is held insuch a way that holds the focal length of the camera front lensconstant, eliminating the need for separate user control of camera focallength. In another embodiment, the housing 14 may have a coupling means15 which enables the module optical system 2 to be securely attached tothe filter adapter ring on many digital cameras. In an embodiment, theoverall dimensions of the module optical system 2 attached to theindependent image recording device 1 may be roughly 10″×5″×5″.Additionally, the housing 14 may also provide a battery pack which caneither be AAs, AAAs, or Lithium-Ion rechargeable batteries to providepower to the composing image acquisition illumination observation source13 and related circuitry thereof. In an embodiment, the housing 14,module optical system 2, consumer digital camera 1 and external flash 61are assembled in such a way as provided in FIGS. 6 and 7.

FIG. 4 illustrates a basic circuitry block diagram of an embodiment ofthe invention which is used to synchronize the operating of taking aphotograph with the consumer camera 1 and triggering the final imageacquisition illumination source 13 of the module optical system 2 inorder to provide adequate illumination for photographing the fundus. Ahot shoe adapter 3 may be connected to the consumer camera 1 and canelectrically communicate when the trigger/shutter 22 sequence of theconsumer camera 1 once initiated. In this embodiment, the hot shoeadapter 3 is able to notify the light and timing circuitry 21 when thetrigger/shutter sequence of the independent image recording device 1 isinitiated. At this time, the lighting and timing circuitry 21 maydisable the composing light source 13 while triggering the finalacquisition light source 13. This enables the module optical system 2and independent image recording device 1 to be easily integrated so asto enable photographing the fundus using the same simple techniques usedfor operating an independent image recording device such as a commercialdigital camera. The final image acquisition illumination source 12intensity is 2-5 orders of magnitude higher than the composing imageillumination source 13 and furthermore is discharged in a total time of100-200 ms. Because of this, the relative intensity of the composingillumination is miniscule in compared to the final image illuminationand thus is not incorporated into the final image. As such, in anembodiment, the need for this triggering circuitry 21 is eliminatedaltogether in order to further simplify the device and increasemanufacturability.

Furthermore, the final image acquisition illumination source 12, whichmay be a xenon flash tube, is able to electrically interface with theconsumer digital camera 1 through the use of a hot shoe adapter 3 thatattaches to the top of the camera. When the shutter button is pressed onthe consumer camera device, the consumer camera device 1 sends anelectronic signal through the hot shoe adapter 3 and the circuitry ofthe module optical system 2. This allows for the user to trigger theshutter and fire the illumination instantaneously. This flash couplingalso takes advantage of the digital camera's through-the-lens (TTL)metering system, and as such allows for the camera to directly integrateauto-exposure features to the novel optical attachment, therebysimplifying user operation inexpensively.

In one embodiment, the final image acquisition illumination source 12 isprovided by an external light source that originates outside of thefundus camera housing. The external light source may be re-routed to thefundus camera housing through a bundle of optical fibers. The distal endof the optical fibers would then act as the final image acquisitionillumination source 12.

In another embodiment, the external light source may be comprised of aninternal flash 65 built-in to the consumer camera device, or mayoriginate in a separate embodiment from an external flash 61, whichmounts to the hot shoe adapter 3 connected to the consumer camera device2. Further, the external flash may not be connected directly to theconsumer camera device, but may be triggered to fire by wirelesscommunication or by firing of the internal flash 65 of the consumercamera device 1. In this embodiment, the external flash device 61 wouldserve as a slave flash and interface with the consumer camera device 1through use of either a wireless or flash slave signal. In thisembodiment the internal flash of the consumer camera device 1 would firewhen the shutter button 22 is pressed, and internal flash 65 wouldtrigger the external flash device 61 to fire simultaneously. Flashintensity would be set manually by the fundus camera user either on thefundus camera housing or ideally on the external flash device itself.

In an embodiment the external flash device 61 would be configured tointerface with the consumer camera device 1 by either use of a hot shoeconnector 3 or PC cord. This embodiment allows direct control of flashintensity by the consumer camera device 1 to obtain an appropriateexposed photograph of the retina. The consumer camera device 1 wouldfire a pre-flash by interfacing with the external flash device 61 toallow the image sensor 53 of the consumer camera device 1 to determineflash intensity necessary to obtain an appropriately exposed image ofthe retina. The consumer camera device 1 would then signal to theexternal flash 61 to fire a final image acquisition flash to acquire thefinal image of the retina based on the settings provided by thepre-flash exposure. In an embodiment the timing between pre-flash andfinal flash exposure would be of a minimum duration necessary to obtainset the appropriate exposure parameters of the external flash, withoutcausing constriction of the pupil of the eye, thereby allowing fornon-mydriatic imaging of the retina.

In a further extension of this embodiment, the xenon flash tube for theexternal flash 61 is placed directly in the housing 14 of the funduscamera and connected to the external flash electrically through anelectrical cord 63. This significantly enhances transmission of thelight produced by the xenon flash over other embodiments that have beendescribed that utilize fiber optic coupling of the external flash to thefundus camera housing. Further, the direct electrical connection allowsthe external flash device to precisely control firing of the xenon tubeboth for initial pre-flash emissions for thru the lens metering andfinal flash firing for performing final image acquisition with thefundus camera. In an embodiment this electrical cord can be disconnectedxenon tube at the site of entry into the fundus camera or at the site ofconnection to the external flash 61. This allows ease of manufacture,fundus camera disassembly and parts replacement should the externalflash device suffer a malfunction and require repair.

Coupling of the illumination pathway thru the front objective lens 4generates undesired back reflections from the eye 5 and front objectivelens 4. Undesired reflections can be reduced through a means ofpolarizing the illumination light from the fundus camera. A firstpolarizer 41 is placed in the illumination optical path 24 prior to thebeamsplitter 7 and after the image mask 10 and second polarizer 43 isplaced in the image acquisition optical path 23 between the beamsplitter7 and consumer camera device 1.

If the first and second polarizers are placed at orientations of 90degrees to one another, the back reflections are significantly reduced.This method utilizes the optical principle of cross polarization,whereby polarized light (e.g., P polarized light) striking a reflectivesurface (e.g. glass, metal) alters the polarization state of reflectedlight to the opposite state (e.g., S polarized light). The secondpolarizer oriented at 90 degrees to the first polarizer permits lightreflected from the retina that remains P polarized to pass to theconsumer camera device, while light reflected from the front objectivelens 4 that is the opposite S polarized is blocked. The polarizers cancomprise either linear or circular polarizers, dependent on whether theconsumer camera device uses contrast based or phase based focusingalgorithms respectively, and may be aligned at angles other than 90degrees to provide variable degrees of rejection of back reflections.The polarizers can be of the wire-grid or thin film type.

In an embodiment, the first 41 and second 43 polarizer may be replacedby a single polarizing beamsplitter. To some degree, this embodiment maybe less utilized over separate polarizers given the complexity ofmanufacture of the polarizing beamsplitter compared to a standard platebeamsplitter 7. To some degree, this embodiment may be less utilizedover separate polarizers given light reflected from the entire retinathat has changed its polarization state is blocked by the polarizingbeamsplitter. This results in a flat retinal image and loss of retinaldetail from retinal structures including but not limited to epiretinalmembrane, refractile drusen, and the internal limiting membrane.

In an embodiment, separate first 41 and second polarizers 43 are used asspecified to improve manufacturability of the fundus camera. Use ofseparate polarizers permits the back reflection produced by the frontobjective lens to be specifically blocked from reaching the image sensorof the consumer camera device 1 by adjusting the size and shape of thesecond polarizer 43 in front of the consumer camera device 1. In oneembodiment the second polarizer 43 can cover a limited central area ofimage sensor 53 of the consumer camera device 1 to block backreflections specifically from the front objective lens 4 while allowingreflected light of all polarization states that are outside of thiscentral limited area to pass to the image sensor of the consumer cameradevice. The embodiment results in an image that contains bothP-polarized and S-polarized light reflected from the retina exceptcentrally.

As the second polarizer 43 also functions effectively as a neutraldensity filter, the final recorded image produced by this embodiment isnecessarily darker centrally than peripherally. This image difference inimage brightness is easily adjusted with post image processing by theimage processing module. In an embodiment, FIG. 10 provides how thesecond polarizer 43 covering a limited central area can be coupled witheither a neutral density filter 46 (or a third polarizer) oriented at adifferent angle to the second polarizer to adjust the image brightnessof the peripheral retina to match that of central retina. Thisembodiment can eliminate the need for post image processing by the imageprocessing module 55 while retaining peripheral P-polarized andS-polarized light to maintain full retinal detail. The neutraldensity/third polarizer 43 can be separated from the second polarizer bya variable distance or they can be placed together with the secondpolarizer inserted into a hole created in the center 44 of the neutraldensity/third polarizer.

In an embodiment of the present invention, the image sensor 53 of theconsumer digital camera 1 may have to be modified to increase thesensitivity to infrared wavelengths to allow for effective non-mydriaticimaging. All consumer cameras come pre-installed with an infraredblocking filter 69 in front of the image sensor. In order to enablenon-mydriatic imaging, this filter must be removed and replaced with afull-spectrum clear glass filter to allow for imaging in the 400 nm to1200 nm wavelengths. This modification can be made either during themanufacturing process of the digital camera itself, or post production.Although the composing illumination source 13 consists of infrared lightin the mydriatic case, the final photograph taken does not record anywavelengths in the infrared range. This is accomplished by adding aninfrared blocking filter 67 and heat absorbing glass 31 in front of thefinal image acquisition illumination source 12. By moving these infraredblocking filters from in front of the imaging sensor 53 to in front ofthe illumination source 12, infrared light contaminations in the finalimage can be eliminated without the need for mechanical flip mirrors,etc. In an embodiment of the non-mydriatic case, a cold mirror filter 11is employed to separate the composing illumination source 13 from thefinal image acquisition illumination source 12. This ensures that when aphotograph is taken, the cold mirror blocks any infrared light from thecomposing light source 13 and therefore only visible light is used fortaking the photograph. Furthermore, by taking advantage of theIR/visible light exposure ratio when the photograph is taken, noadditional circuitry is required to communicate between the infraredcomposing illumination 13 and the final image acquisition illumination12. A camera's exposure time (set at 1/640 s for example) only allows afraction of the infrared composing light 13 to be captured by theimaging sensor 53. In contrast, the 1/640 s exposure time is more thanenough to account for nearly 100% of the visible light outputted fromthe external flash 12/61 which can fully discharge on the order of1/2000 s. The combination of these two temporal characteristics of thelight output causes the IR/Visible ratio in the final image to bevirtually null, thereby simplifying the manufacturing process of theportable fundus camera.

It should be noted that this aspect of the embodiment of allows for theportable fundus camera to use the same imaging sensor 53 for bothobservation and photographing the fundus of the eye in the non-mydriaticcase. This allows both the composing and final image acquisition imagesensors to be incorporated within the consumer camera 1 and eliminatesthe need for separate imaging elements. The need for two separatephotoelectric imaging elements increases the total size of the system.In brief, this feature may allow for simplification of the non-mydriaticoptical and imaging system by taking advantage of the IR/visible lightexposure ratio when the photograph is taken. The light output causes theIR/Visible ratio in the final image to be virtually null, resulting in adesign that allows for the use of a consumer digital camera 1 incombination with the module optical system 2 for both observing andphotographing the fundus at a very low cost.

The consumer camera device in one embodiment has a built-in display unitfor composing and focusing (e.g. Liveview) as well as reviewing thedigital image of the retina that has been acquired and stored in thedevice. In an embodiment this display consists of a liquid crystaldisplay (LCD) 51 and is further comprised of a display that can bepositioned at multiple orientations relative to the camera body (e.g.flip screen). In an embodiment the orientation of the screen can berotated 180 degrees in both vertical and horizontal orientations toprovide a mirror image display relative to its usual position on thecamera body.

Some consumer camera devices possess a rotatable LCD capability as aninherent feature of the device (e.g. Canon G11). These cameras are ableto detect when the LCD 51 has been placed into a mirror orientation(e.g., through a digital switch) and through software processing areable to digitally flip the displayed image sensor of the consumer cameradevice so that the user sees the usual and correct orientation of theimage on the image sensor 53. In an embodiment, this capability fordetecting the LCD has placed into a mirror orientation is disabled(e.g., through removal of the digital switch). As the camera is not ableto detect that the LCD 53 is in a mirror orientation, the image from theimage sensor is now displayed in a mirror orientation.

The front objective lens 4 of the fundus camera produces an image of theretina that is in a mirror orientation. Thus, when displaying this imageon the LCD 53, if the LCD were left in its usual position, the userwould see a mirror orientation of the retina. This can potentiallyconfuse the user as movement of the camera to the left will result inthe image moving to the right, and similarly movement of the camera tothe right will result in the image moving to the left. By flipping theLCD 53 into a mirror orientation, the combination of mirror LCDorientation and mirror retinal image orientation cancel one another toproduce an image of the retina on the LCD that is now in a non-mirroredorientation. Thus, when the user moves the camera to the right, theimage on the LCD will now move to the right, and when the user moves thecamera to the left, the image on the LCD will now move to the left. Thisembodiment allows the user to more easily align the camera with the eyewhen looking at the LCD by using movements that are more natural tothem.

Additionally, in an embodiment, the settings for the consumer digitalcamera 1 may be present during the manufacturing process using theuser-definable custom settings programs already built into the camera.Various aspects such as the focal length, initial focus, autofocus,manual focus, white balance, noise reduction, image stabilization,contrast, sharpness, aperture, ISO, and shutter speed may all be pre-setto simplify operation of the device. This allows for the user to operatethe camera and produce a successful retinal image by just “pointing andshooting.” It should be appreciated that these settings may beprogrammed into the camera permanent memory, and can only be changed bymanually resetting the camera through the menus system. Losing powerwill not erase these important settings.

In an embodiment, operation of the portable fundus camera will consistof the user turning on the consumer digital camera and also turning on aswitch to power the module optical system located on the housing 14. Theuser may now aim the camera toward the patient's eye. The live view LCDscreen 51 on the digital camera will show in real time the image of thepatient's fundus and also gives a sense of where the camera most bemoved in order to center it on the pupil. When the image is composed,the LCD screen 51 on the camera will show a preview of the fundus image.The user will find a suitable focus point (such as a vessel or the opticnerve) and half depress the shutter to auto-focus the camera. Ifauto-focus cannot be achieved, the user can switch the camera into itsmanual focus mode and achieve proper focus by that means. Once focusingis completed, the user can now depress the shutter button completely.This will trigger the hot shoe adapter 3 to fire off the photographinglight source 13 in the module optical system 2 to properly expose theimage. In an embodiment, the shutter speed chosen for image capture wasset to 1/500 s to eliminate motion blur of both the user as well as thepatient's eye. The LCD 51 will now show a review of the previously takenimage. If the user is not satisfied, he or she may delete the pictureand repeat the process again. Exposure levels can also be adjusted byvarying the flash power in small increments by means of a switch on theattachment.

In an embodiment, accurate patient identification can be achieved bytaking the picture of a patient ID card before any pictures of theretina are taken. In this way, the image files will run in series andcorrespond to a new patient whenever a picture of a patient ID cardexists. The images taken may be stored on the memory card for laterclinical use by a certified and licensed medical practitioner. Thememory card can be hooked up to wirelessly and automatically uploadedinto an archiving system as well through the use of a WiFi enabled SDcard (EyeFi) or the like. Telemedicine practices may be used where theimages taken will be reviewed by ophthalmologists in a remote location.If the image shows that the patient has a disease or defect, the patientcan then be referred to a specialist for more testing and treatment.

In an embodiment the fundus camera will have an additional imageprocessing module to enhance the capability of the camera to performcomposing and focusing of the image of the retina as well as enhance thefinal image of the retina recorded by the consumer camera device. In oneembodiment, the image processing module is contained within the consumercamera device 1 and is interface with the user of the fundus camerathrough the LCD screen 51 of the consumer camera device. In anotherembodiment, the image processing module is contained as a separatedevice outside of the fundus camera. In an embodiment image processingis performed by the image processing module at either the local orremote location to which the fundus camera transmits its stored imagesof the retina.

The image of the retina formed by the front objective lens 4 of thefundus camera is in a mirror orientation. In an embodiment, the funduscamera image processing module will flip the image on the image sensor53 of the consumer camera device in both horizontal and vertical axesand display the resultant non-mirror image on the LCD of the consumercamera device. In another embodiment, the image recorded by the consumercamera device retains its mirror orientation. A local or remote imageprocessing module of the fundus camera is able to flip the image of theretina recorded by the consumer camera device along both horizontal andvertical axes to display the correct orientation of the retina to theuser reviewing the recorded images.

In another embodiment, the image processing module of the fundus camerais able to digitally remove back light reflections recorded by the imagesensor of the consumer camera device 1. This removal can be accomplishedby a suitable software algorithm that can detect these back lightreflections and then remove them digitally from the recorded image. Inone embodiment this software algorithm is able to detect the back lightreflection by differences in the optical properties of the reflectionsby one or more of the following: spectral wavelength content, size,brightness, contrast, or hue of the reflection compared to the opticalproperties of the remainder of the recorded image. In one embodiment ofthe software algorithm, the algorithm and related computer logic code isable to subtract the content of the back light reflection and retain thecontent of the retinal image underlying the back light reflection.

In an embodiment, the spectral content of the back light reflections isused to identify the position and size of the reflections in therecorded retinal image. The light reflected from the retina containsprimarily green and red spectral components, while the back lightreflected from the front objective lens contains spectral contentprimarily in the blue and green part of the visible spectrum. Byspecifically analyzing the blue channel of the retinal image, thespectral content of the back light reflection can be identified and usedto construct an image mask. The relative spectral signal of the backlight reflection can then be combined with the image mask to digitallysubtract the back light reflection from the stored retinal image torecover the spectral content of the retina that underlies thesereflections—FIG. 11

In a separate embodiment, multiple recorded images of the retina fromthe consumer camera device can be used by the software algorithm toconstruct a final image in which the back light reflections are removed.The back light reflections can be identified by spectral content,location, size, brightness, hue as previously specified. Once the backlight reflections are identified on each recorded image, the recordedimages are then combined by the software algorithm. In locations, whereimages overlap with one another, the software algorithm chooses toretain the image content from images that do not have identified backlight reflections in these location. In other locations where imagesoverlap and there is no back light reflection, the software algorithmchooses the image content to be displayed through another evaluation(e.g., the image with the best contrast) or by averaging the content ofthe two images where they overlap.) The software algorithm will be ableto correctly align and blend the content of the two images by usingsimilar landmarks in each image (e.g. patterns of blood vessel orlocation of optic nerve). Thus, the final combined image produced by thesoftware algorithm does not contain any back light reflections and is ablended composite of the multiple images.

In one embodiment of the fundus camera a central polarizer is used toremove the central back light reflection produced by the front objectivelens of the fundus camera. This configuration of polarizer isadvantageous because it removes the central back light reflection whileretaining the image of the retina that underlies the central backreflection. Further, this configuration of polarizer preserves theretinal reflections/details from the remainder of the image field exceptover the central part of the image. The resultant image in practice mayhave mild changes in brightness and contrast over the central part ofthe image corresponding to size and location of the polarizer. In oneembodiment of the image processing module this mild imbalance isautomatically corrected by the appropriate software algorithm. Theresultant image following digital correction of central white balancehas equivalent white balance over the full extent of the image,enhancing the recorded image produced by the fundus camera. In oneembodiment this digital correction is performed in the consumer cameraitself In another embodiment this digital correction is performedfollowing local or remote transmission of the recorded image from thefundus camera.

In an embodiment the fundus camera will contain a transmission module tocommunicate the images to either a local workstation or to a remotelocation for image review and diagnostic assessment. This transmissionmodule may be included in the fundus camera housing 14 or be a separatemodule from the fundus camera housing. The transmission module mayconnect either locally or remotely by use of a wired or wirelessconnection (e.g. a cord connecting from the fundus camera to a locallaptop computer for image review). In an embodiment, the images arecommunicated wirelessly through either radio frequency, bluetooth, acellular or wireless network. The images are transmitted locally and toa remote location for independent archiving outside of the fundus cameraitself.

In an embodiment, a data storage card (e.g., SD flash memory card) isused to store images for the consumer camera device. This data storagecard has the capability of both data storage and wireless transmissionof these stored images both locally and to a remote location. Oneparticular enumeration of the data storage and wireless transmissiondevice would be a commercially available Eye-fi card. The local and/orremote location consists of device (e.g. computer) that archives thestored images from the consumer camera device. Multiple embodiments maycomprise this device but it is generally understood to include at leastone of the following: a user, a processor, a display, a database, anarchive, or any combination thereof. Beyond archival of the storedimages on the consumer camera device, the transmission module wouldallow for communication of images of the fundus to be reviewed forpotential pathology by skilled practitioners (e.g. ophthalmologists oroptometrists) at a remote location.

FIG. 11A and FIG. 11B illustrate the effect of the digital subtractionof spectral content of back light reflections practicing an embodimentof the present invention. FIG. 11A provides a recorded retinal imageprior to digital subtraction of back light reflections. FIG. 11Bprovides a recorded retinal image after digital subtraction of backlight reflection.

FIG. 12A and FIG. 12B illustrate the effect of the digital subtractionof back light reflections by combining multiple images practicing anembodiment of the present invention. Retinal image no. 1 (FIG. 12A) iscombined with retinal image no. 2 (FIG. 12B) to provide a combined image(FIG. 12C).

FIG. 13A and FIG. 13B illustrate the effect of digital enhancement ofcentral white balance practicing an embodiment of the present invention.FIG. 13A provides a recorded retinal image prior to digital enhancementof central white balance. FIG. 13B provides a recorded retinal imageafter digital enhancement of central white balance practicing anembodiment of the present invention.

FIG. 14A and FIG. 14B illustrate practicing an embodiment of the presentinvention. FIG. 14A illustrates an embodiment using a Canon G10 consumercamera device. FIG. 14B illustrates practicing a mydriatic embodimentusing the Canon G10 consumer camera device on a human eye. FIG. 14Cillustrates practicing a non-mydriatic embodiment using the Canon G10consumer camera device on a human eye. FIG. 15A, FIG. 15B, and FIG. 15Cillustrate practicing an embodiment of the present invention. FIG. 15Aand FIG. 15B illustrate an embodiment using a Panasonic Lumix G2consumer camera device. FIG. 15C illustrates the resultant fundus imagepracticing a mydriatic embodiment.

In summary, an aspect of an embodiment or various embodiments of thepresent invention comprises, among other things, a novel and verylow-cost portable fundus camera. An aspect of various embodiments of thepresent invention may provide a number of novel and non-obviousfeatures, elements and characteristics, such as but not limited thereto,the following: the system may rely on a consumer digital camera tocapture the image of the fundus, conduct the focusing, trigger theillumination light, provide image stabilization, and enable in-depthuser control. The novel portable fundus camera has the ability to takenon-mydriatic images of the fundus. In addition, an aspect of anembodiment of the present invention comprises the ability for the systemto be completely battery powered and operated. There will notnecessarily by a cord or connection to conventional external powersupply. Furthermore, the system will not require the existence of aseparate eyepiece (necessarily) for user viewing and composition of thefundus image. Accurate composition and focus may be achieved from theelectronic LiveView screen of the digital camera. Additionally, throughthe use of infrared and visible spectrum LED technology in addition to axenon flash unit, an aspect of embodiments of the present inventionprovides that the portable camera will be able to function as anon-mydriatic camera.

An aspect of one or various embodiments of the present invention mayprovide a number of advantages, such as but not limited thereto, thefollowing:

True Portability—Other cameras require a dedicated, wired power source.An embodiment of the present invention may be, for example, be operatedby AA/AAA batteries in addition to the lithium battery supplied with thedigital camera. This provides a distinct advantage, primarily inallowing for clinicians to diagnose patients in remote screeninglocations in developing countries as well as improving workflow when onemust move from exam room to exam room.

Ease-of-Use—Because an embodiment of the camera may use a consumerdigital camera as its base, operation of the camera will come easily andnaturally to most users. With a brief 5 minute introduction on how tooperate the camera, for example, untrained medical staff will be able toobtain clear, accurate images of a patient's retina. In contrast, funduscameras currently on the market require a trained retinal photographerto operate.

Low Cost—An embodiment of the present invention may be able to be markedat a fraction of the cost of similar products on the market. This willfinancially enable smaller clinics in the US as well as well aspractitioners in developing nations to provide adequate screeningopportunities and thus reduce cases of preventable blindness worldwide.

High Resolution Images—In an embodiment of the camera, through the useof the digital camera sensor, as aspect of an embodiment of theinvention will also provide the ability to take pictures up to 15 MP,for example. Other “portable” fundus cameras only have a resolution of 2MP.

EXAMPLES

Practice of an aspect of an embodiment (or embodiments) of the inventionwill be still more fully understood from the following examples, whichare presented herein for illustration only and should not be construedas limiting the invention in any way.

Example Set No. 1

Referring to the figures throughout, an aspect of an embodiment of thepresent invention provides a hand-held portable fundus camera system.The hand held fundus camera system may comprise: a module optical system[2] capable of being integrated with a consumer camera device [1] forauto focus photography by the consumer camera device of the fundus of aneye [5]. The module optical system [2] may comprise: a composing imageacquisition illumination observation source [13] (e.g., photographinglight source); a final image acquisition illumination source [12] (e.g.observation light source); an optical separator and transmitting means[33] (e.g., IR filter [67], heat absorbing glass [31], cold mirror/beamsplitter [11] or the like) for separating and transmitting the composingimage acquisition observation illumination source [13] and the finalimage acquisition illumination source [12] to an image mask [10], ofwhich is relayed to the retina of the fundus through the use of aredirecting mirror [8], a beam splitter [7] and a front objective lens[4]. The image mask [10] may be configured to provide light thatilluminates the retina to output an image that is relayed through theobjective lens [4] and captured by the consumer camera [1] to provide animage of the retina [5]. Also included is a module interface system [15](e.g. macro lenses, physical couplings, macro extension ring) tointegrate the module optical system [2] with the consumer camera device[1]. It should be appreciated that the module interface system [15]enhances the macro focusing capability of the consumer camera device [1]to enable auto-focus photography by the consumer camera device [1]of thefundus image produced by the front objective lens [4].

The image mask [10] may configured to create a bundled donut of light.The module optical system [2] may further comprise a diffuser [17]. Themodule optical system [2] may further comprises a rear converging lens[9]. The rear converging lens [9] optically couples an illuminationoptical path [24] to an imaging acquisition path [23]. The moduleoptical system [2] may further comprise a light trap [6] disposed abovethe beam splitter [7] whereby light passing through the beam splitter[7] along the illumination optical path [23] and not redirected alongthe module imaging optical path [24] is absorbed by the light trap [7].The light trap [6] may be lined with at least one of light absorbingmaterial, black absorbing felt, absorbing neutral density filter, or anycombination thereof. The light trap [6] may further comprises wallswhich cause light to reflect internally within the light trap [6]. Thefundus camera may further comprises a housing [14] that comprises themodule optical system [2] and configured to couple the module opticalsystem [2] to the consumer camera device [1]. The housing [14] may beconfigured provide an optical barrier that separates the illuminationoptical path [24] from the imaging acquisition optical path [23] exceptbetween the beam splitter [7] and the redirecting mirror [8] of theillumination optical path [24]. The housing [14] may be configured toallow detachment of the illumination optical path [24] from the imagingacquisition optical path [23] to enhance manufacturability andmaintenance of the fundus camera. In an approach, distance between thefront objective lens [4] and the rear converging lens [9] and the imagemask [10] is optimized to reduce back-reflections while still providingadequate illumination of the retina. The size, position, and focallength of the rear converging lens [9] in combination with the frontobjective lens [4] focuses the bundled donut of light created by theimage mask [10] posterior to the cornea. The composing image acquisitionillumination observation light source [13] may comprise a visible lightsource. The visible light source [13] may be comprise an LED. Thevisible light source [13] may comprise a white, red, green, or blue LEDor a combination thereof. The blue LED provides a wavelength capable ofexciting fluorescein dye for fluorescein angiography. The final imageacquisition illumination source [12] may comprise a xenon flash bulb.The final image acquisition source [12] further comprises a reflectorfor the xenon flash bulb. The beam splitter [7] may comprise a standard50 percent reflection and 50 transmission mirror. The beam splitter [7]comprises a less than 50 percent reflection and greater than 50 percenttransmission mirror to enhance transmission of the image of the retinaproduced by the front objective lens [4] to the consumer camera device[1]. The beam splitter [7] comprises either at least one of dichroicfilter, bi-dichroic, or triple dichroic filter, or any combinationthereof The beam splitter [7] may comprise a red, green, blue tripledichroic. The beamsplitter [7] reflects blue light configured forexciting fluorescein dye and transmits the resulting reflected lightfrom the eye to the consumer camera device [1]. The housing [14]encloses module optical system [2] and may be configured to couple themodule optical system [2]to the consumer camera device [1]. The housing[14] may further comprises electrical circuitry to interface the moduleoptical system [2] with the consumer camera device [1]. The housing [14]may further comprises a battery-based power source [20]. The housing[14] may be in communication with or dispose to the module interfacesystem [15], having a mount for the front camera device lens [35] of theconsumer camera device [1] to maintain the front camera device lens [35]at a constant focal distance for focusing on the image of the retinaproduced by the front objective lens [4]. The module interface system[15] may further comprise a macro extension ring, the macro extensionring being integrated into the housing [14]of the fundus camera (e.g.,to enhance manufacturability of the fundus camera). The module interfacesystem [15] may further comprise a macro lens [37] and/or a macroextension [39] to enhance the consumer camera device's [1] ability tofocus on the image of the retina produced by the consumer camera device[1]. The consumer camera device [1] comprising a front camera devicelens [35], wherein the macro extension ring is positioned to place thecentral focal point of the camera device front lens [35] at the locationof the image formed by the front objective lens [4] (thereby enhancingability of the consumer camera to use its entire focal range bothpositive and negative to allow it to focus on patients with a range ofeyeglass prescriptions). The module interface system [15] may furthercomprise a macro lens to enhance the consumer camera device's ability tofocus on the image of the retina produced by the consumer digital cameradevice [1]. The consumer camera device [1] may comprising a front cameradevice lens [35], wherein the macro lens is positioned to place thecentral focal point of the camera device front lens [35] at the locationof the image formed by the front objective lens [4] (thereby enhancingability of the consumer camera to use its entire focal range bothpositive and negative to allow it to focus on patients with a range ofeyeglass prescriptions). The consumer camera device [1] may furthercomprise at least one of: auto-focusing elements; auto-exposureelements; image stabilization technology; means for taking macro images;LCD for observing the image of the retina; flash illumination forenhancing image recorded by the consumer camera; or data storage systemfor recording of the image of the retina (or any other system, device,composition, material, computer program logic, computer processing, orcomponent as desired or required). The data storage system may furthercomprise a flash memory device for storing images of the fundus. Thefundus camera may further comprise a transmission module forcommunication to a local and/or remote location. The transmission modulemay further comprise a network enabled wireless data transfer systemwith means for transferring recorded images of the fundus [5] to anindependent archival system. The transmission module may furthercomprise a combination data storage device and wireless data transfersystem. The combination data storage device and wireless data transfersystem may further comprise an Eye-fi card or the like. The local and/orremote location may be at least one of a user, a processor, a display, adatabase, an archive, or any combination thereof. The transmissionmodule may provide a means, system or mechanism for the communication ofimages of the fundus [5] to be reviewed by ophthalmologists or careprovider in a remote location. The fundus camera may further comprise anLCD screen (or other type of displays as desired or required), wherebythe LCD screen [51] may be configured to show a live image of the imageon an image sensor [53] of the consumer camera device [1]. The LCDscreen [51] may be a flip screen type comprising a rotation mechanismconfigured to allow inversion of horizontal and vertical axes of theflip screen LCD [51]. The flip screen [51] may further comprise thecapability to display a mirror image display of the image on the imagesensor [53] of the consumer camera device [1] to enhance ease ofalignment of camera with the patients eye. The fundus camera may furthercomprise an image processing module [55], wherein the consumer cameradevice comprising an image sensor [53]. The image processing module [55]may be configured to enhance the image of the retina recorded by theimage sensor [53] of the consumer camera device [1]. The imageprocessing module [55] may be configured to display a mirror image ofthe image of the retina on the image sensor [53] of the consumer cameradevice [1]. The image processing module [55] may be configured toeliminate back light reflections from the image of the retina recordedby the image sensor [53] of the consumer camera device [1]. Theelimination of back light reflections identifies the back lightreflections from the retinal image recorded by the image sensor [53] ofthe consumer camera device [1] by comparing the optical properties ofthe back light reflections with the optical properties of the retinalimage. The optical properties may include spectral content, size,brightness, and/or contrast. The image processing module [55] may beconfigured to subtract the optical properties of the back lightreflections with the optical properties of the retinal image to removethe back light reflections and restore the retinal image that isobscured by the back light reflections. The image processing module [55]may be configured to combine overlapping images of the retina recordedby the consumer camera device [1], wherein the back reflection isremoved from the final combined image by choosing areas of eachindividual image that do not include the optical properties of the backreflections. The image processing module [55] being configured to storea mirror image of the image from the image sensor [53] of the consumercamera device [1] to correct the inverted orientation of the image fromthe image sensor [53] of the consumer camera device [1]. The imageprocessing module [55] may be configured to adjust the exposure of therecorded image of the consumer camera device [1] to even theillumination across the image recorded of the consumer camera device[1]. The front objective lens [4] may be a double aspheric lens, anaspheric convex lens, a convex-convex lens, or a convex-plano lens (oras desired or required). The front objective lens [4] may haveantireflection coatings to reduce illumination source reflections. Thefront objective lens [4] may be a standard lens normally used forindirect opthalmoscopy. The front objective lens [4] may have aneffective power of about 20 D to about 22 D (e.g., Volk DigitalClearfield lens Ocular Instruments OI-22M lens) to provide about 50°field of view of the fundus [5]. The front objective lens [4] may besecured by a lens mount [59] with a front converging lens mask that isconfigured to reduce edge image artifacts from the front objective lens[4]. The fundus camera may further comprise a polarizer means, system,device for polarizing light to reduce back light reflections from thefundus camera [2]. The polarizer means may comprise a first polarizer[41] that may be placed in the illumination optical path [24] and asecond polarizer [43] is placed in the image acquisition optical path[23]. The first polarizer [41] and the second polarizer [43] may beoriented at different angles relative to one another (or as desired orrequired). The first polarizer [41] and the second polarizer [43] may beoriented at about 90 degrees to one another to enhance crosspolarization to reduce back light reflections from the fundus camera[2]. The first polarizer [41] and the second polarizer [41] may beplaced after the image mask [10] and between the beamsplitter [7] andthe front lens [35] of the consumer camera device [2]. The secondpolarizer [43] may comprises a circle [44] of dimensions needed to crosspolarize only the reflection from the front objective lens [4] to reduceback light reflections from the front objective lens [4]. The secondpolarizer [43] may be further comprised of a combination of polarizer'soriented at different angles to one another. The second polarizer [43]may comprise one of a smaller polarizer in the shape of a small circle[44], and one of a larger polarizer [46] with a small circle cut fromthe center of the larger polarizer, and wherein the smaller circlepolarizer [44] is positioned before the larger polarizer at the locationof the small cut circle, or is positioned within the small cut circle ofthe larger polarizer, and wherein the smaller circle polarizer isoriented at 90 degrees to the first polarizer [41] and larger polarizeris oriented in the same orientation as the first polarizer [41]. Thepolarizer means may comprises linear polarizers. The polarizer meanscomprises circular polarizers (or as desired or required).

Example Set No. 2

Referring to the figures throughout, an aspect of an embodiment of thepresent invention provides a hand-held portable fundus camera system.The hand-held portable fundus camera system may comprise a moduleoptical system [2] capable of being integrated with a consumer cameradevice [1] for photographing the fundus of an eye [5]. The moduleoptical system [2] may comprise: a composing image acquisitionillumination observation source [13] (e.g., photographing light source);a final image acquisition illumination source [12] (e.g. observationlight source); and an optical separator and transmitting means [33](e.g., IR filter [67], heat absorbing glass [31], cold mirror/beamsplitter [11]) for separating and transmitting the composing imageacquisition observation illumination source [13] and the final imageacquisition illumination source [12] to an image mask [10] the imagemask [10], of which is relayed to the retina of the fundus [5] throughthe use of a redirecting mirror [8], a beam splitter [7] and a frontconverging lens [4]. The module optical system [2] may further comprise:the image mask [10] being configured to provide light that illuminatesthe retina to output an image that is relayed through the frontobjective lens [4] and captured by the consumer camera device [1] toprovide an image of the retina [5]. The consumer camera device [1] maycomprise a consumer point and shoot or digital single lens reflex system(DSLR) module for automated image capture and review. The consumercamera device [1] may further comprise: an external flash device [61]; ahot shoe adapter [3] in communication with the external flash device[61], wherein the captured image being provided by the consumer cameradevice [1] being in communication with the final image acquisitionillumination source [12]. Moreover, the captured image may be properlyexposed by the consumer camera device [1] being in communication withthe final image acquisition illumination source [12], wherein theexternal flash device [61] comprises through the lens (TTL) metering toallow the consumer camera device [1] to provide properly exposed imagesof the retina [5].

Further, the consumer camera device [1] may further comprises at leastone of: auto-focusing elements; auto-exposure elements; imagestabilization technology; means for taking macro images; LCD forobserving the image of the retina; internal flash illumination forenhancing image recorded by the consumer camera; or data storage systemfor recording of the image of the retina (or any other system, device,composition, material, computer program logic, computer processing, orcomponent as desired or required). The final image acquisitionillumination source [12] may be delivered by a transmission channel [63]to the module optical system [2]. The final image acquisitionillumination source [12] may be delivered by the transmission channel[63] from the internal flash illumination device [65] of the consumercamera device [1], wherein the transmission channel comprise opticalfibers. The final image acquisition illumination source [12] may bedelivered by the transmission channel [63] from the external flashillumination source [61] of the consumer camera device [1], wherein thetransmission channel comprise optical fibers. The external flash device[61] further comprises a manual slave flash. The manual slave flashfurther comprises an optical sensor triggered by the internal flashillumination device [65] of the consumer camera device [1]. The manualslave flash further comprises a xenon flash tube separate from themanual slave flash. The xenon flash tube is connected by a transmissionchannel [63] to the electronics of the manual slave flash, and whereinthe transmission channel [63] is an electronic transmission. Theelectronic transmission channel [63] has a connector to allow detachmentfrom the xenon flash tube. The fundus camera may further comprise ahousing [14] that includes the module optical system [2], wherein thexenon flash tube is disposed directly on the fundus camera housing todeliver the final image acquisition illumination source [12]. Theexternal flash device [61] may be further comprised of a through thelens (TTL) metering flash. The external flash illumination device [61]from the through the lens (TTL) metering flash may be configured to bedirectly controlled by the consumer camera device [1] to control imageexposure. The fundus camera may further comprises a hot shoe adapter[3], wherein the use of the consumer camera device [1] is synchronizedwith the use of the module optical system [2] by means of the hot shoeadapter [3]; and wherein the through the lens (TTL) metering flash isfurther comprises a connection to the hot shoe adapter [3] to allowcontrol of the external flash illumination device [61] by the consumercamera device [1]. The through the lens (TTL) metering flash may furthercomprises a xenon flash tube separate from the through the lens (TTL)metering flash. The xenon flash tube may be connected by a transmissionchannel [63] (e.g., cord or other means as desired or required) to theelectronics of the through the lens (TTL) metering flash. Thetransmission channel [63] (e.g., cord, wire, integrated circuit,circuit, any transmission or communication means, or the like) has aconnector to allow detachment from the xenon flash tube. The funduscamera may further comprises a housing [14] that comprises the moduleoptical system [2], wherein the xenon flash tube is disposed directlythe fundus camera housing to deliver the final image acquisitionillumination source [12]. The xenon flash tube distance to the imagemask [10] may be minimized to enhance transmission of flash to allow useof lower power flash for the final image acquisition illumination source[12]. The external flash device [61] my be configured to emit apre-flash to control image exposure by the consumer camera device [1].The duration of the pre-flash and the time period between the pre-flashand the final flash emission may be of a duration to prevent pupilconstriction prior to the final flash emission. The fundus camera mayfurther comprises a hot shoe adapter [3], wherein the use of theconsumer camera device [1] may be synchronized with the use of themodule optical system [2] by means of the hot shoe adapter [3]. The hotshoe adapter [3] comprises an electrical connection to the externalflash device [61] to provide through the lens (TTL) control of imageexposure by the consumer camera device [1].

Example Set No. 3

Referring to the figures throughout, an aspect of an embodiment of thepresent invention provides a hand-held portable fundus camera systemcomprising. The hand-held portable fundus camera system may comprise amodule optical system [2] capable of being integrated with a consumercamera device [1] for photographing the fundus of an eye [5] usinginfrared illumination for focusing of the image by the consumer cameradevice [1]. The module optical system [2] may comprise: a composingimage acquisition illumination observation source [13] (e.g., old:photographing light source), wherein the wavelength of the imageacquisition illumination source is infrared; a final image acquisitionillumination source [12] (e.g., xenon flash tube); and an opticalseparator and transmitting means [33] (e.g., IR filter [67], heatabsorbing glass [31], cold mirror/beam splitter [11]]) for separatingand transmitting the composing image acquisition illuminationobservation source [13] and the final image acquisition illuminationsource [12] to an image mask [10], of which is relayed to the retina ofthe fundus through the use of a redirecting mirror [8], a beam splitter[7] and a front objective lens [4]. The module optical system [2] mayfurther comprise the image mask [10] configured to provide light thatilluminates the retina to output an image that is relayed through thefront objective lens [4] and captured by the consumer camera [1] toprovide an image of the retina [5]. The optical separator andtransmitting means [33] may further comprise at least one or more of‘a’, or ‘c’. Whereby ‘a’, ‘b’, or ‘c’ may include the following: a)separating and transmitting the composing image acquisition illuminationobservation source [13] that is of infrared wavelengths and the finalimage acquisition illumination source [12] that is of visiblewavelengths; b)separating and transmitting the composing imageacquisition illumination observation source [13] that is of visible andinfrared wavelengths and the final image acquisition observationillumination source [12] that is of visible and infrared wavelengths; c)separating and transmitting the composing image acquisition illuminationobservation source [13] that is of visible wavelengths and the finalimage acquisition illumination source [12] that is of infraredwavelengths. The fundus camera may further comprises of at least one of:an infrared cutoff filter [67] optically disposed between the finalimage acquisition illumination source [12] and the optical separator andtransmitting means [33]; or an infrared cutoff filter [67] opticallydisposed between the composing image acquisition illumination source[13] and the optical separator and transmitting means [33]. And whereinthe consumer camera device [1] may comprise a consumer point and shootor digital single lens reflex system module for automated image captureand review, whereby an infrared filter has been removed or bypassed fromthe consumer point and shoot or the digital single lens reflex systemmodule and replaced with a full spectrum filter [69]. The consumercamera device [1] may further comprises: an external flash device [61];a hot shoe adapter [3] in communication with the external flash device[61], whereby the captured image being provided by the consumer cameradevice [1] being in communication with the final image acquisitionillumination source [12]; and wherein the captured image being properlyexposed by the consumer camera device [1] being in communication withthe final image acquisition illumination source [12]; and wherein theexternal flash device [61] comprises through the lens (TTL) metering toallow the consumer camera device [1] to provide properly exposed imagesof the retina [5].

The infrared cutoff filter [67] may comprises at least one of: anultraviolet cutoff filter or a visible cutoff filter. The infraredfilter may be configured to attenuate infrared wavelength from finalimage acquisition source is further comprised of at least one of thefollowing: heat absorbing glass; infrared cutoff filter; or cold mirror.The fundus camera may be used for non-dilated (non-mydriatic)photographing of the fundus of an eye. The final illuminationacquisition source and the composing image acquisition illuminationsource may be of different optical paths. The final illuminationacquisition source and the composing image acquisition illuminationsource may be of different power levels enhancing patient comfort duringfocusing of the fundus camera. The different power levels may besufficiently different, with the final image acquisition source brighterthan the composing image acquisition illumination source, so thatshutter speed of the consumer camera device can be set at the speed thatresults in capture of light from the final image acquisition source withsignificantly reduced capture of light from the composing imageacquisition source without turning off the composing image acquisitionsource during image capture. The composing image acquisition source maybe infrared, but has reduced contribution to the image on the imagesensor of the consumer camera device [1] during the image capture by theconsumer camera device due to an increased shutter speed determined by asignificantly brighter final image acquisition source. The image mask[10] may be configured to create a bundled donut of light. The whereinthe module optical system [2] further comprises a rear converging lens[9]; wherein the rear converging lens [9] optically couples anillumination optical path [24] to an imaging acquisition path [23];wherein the illumination optical path [24] is at first directed parallelto the module imaging acquisition optical path [23]; and wherein theredirecting mirror [8] redirects the illumination optical path so thatit is oriented perpendicular to the module imaging optical path. Themodule illumination optical system [2] may further comprises a diffuser[17]. The module optical system [2] may further comprises a rearconverging lens [9]. The rear converging lens optically couples theillumination path [24] to the module imaging acquisition optical path[23]. The distance between the front objective lens the rear converginglens and the image mask may be optimized to reduce back-reflectionswhile still providing adequate illumination of the retina. The size,position, and focal length of the rear converging lens in combinationwith the front objective lens [4] focuses the bundled donut of lightcreated by the image mask posterior to the cornea. The rear converginglens may be placed between the redirecting mirror [8] and the beamsplitter to reduce fundus camera size and increase illumination. Therear converging lens may be placed between the redirecting mirror [8]and the image mask. The composing image acquisition illuminationobservation light source [13] may comprise a visible light source. Thecomposing image acquisition illumination observation light source [13]may comprise an LED or the like. The LED may comprise a white, red,green, or blue LED or a combination thereof. The blue LED may be awavelength capable of exciting fluorescein dye for fluoresceinangiography. The composing image acquisition illumination observationlight source [13] may comprise an infrared light source. The composingimage acquisition illumination observation light source [13] maycomprises an LED or the like. The LED may comprises a single or multiemitter infrared LED of 850 nm. The fundus may further comprise a LEDdriver [21] (e.g., lighting and timing circuitry or the like) to supplyelectrical power to the LED. The LED driver [21] may further comprise aboost converter to increase battery voltage to supply electrical powerto the LED and a buck converter to supply power from the boost converterto the LED. The final image acquisition illumination source [12] maycomprise visible and infrared light sources with means to switch betweenusing the visible light source and the infrared light source. The finalimage acquisition illumination source [12] may comprise a xenon flashbulb. The final image acquisition illumination source [12] may furthercomprise a reflector for the xenon flash bulb. The final imageacquisition illumination source [12] may further comprise a filter [67]to select a range of wavelengths to transmit in the final imageacquisition illumination source [12]. The filter [67] of the final imageacquisition illumination source [12] may be an IR cutoff filter or thelike. The filter [67] of the final image acquisition illumination source[12] may be a UV cutoff filter. The beam splitter [7] may comprise astandard 50 percent reflection and 50 transmission mirror. The beamsplitter [7] may have a spectral range in both visible and infraredspectrum. The beam splitter may comprise a less than 50 percentreflection and greater than 50 percent transmission mirror to enhancetransmission of the image of the retina produced by the front objectivelens [4] to the consumer camera device [1]. The beam splitter may have aspectral range in both visible and infrared spectrum. The beam splitter[7] may comprise either at least one of dichroic filter, bi-dichroic,triple dichroic, quad dichroic filter, or any combination thereof. Thebeam splitter being may be configured to transmit infrared wavelengths.The beam splitter may comprise an infrared, red, green, blue quaddichroic. The beamsplitter may be configured to reflect blue lightcapable of exciting fluorescein dye and transmits the resultingreflected light from the eye to the consumer camera. The beam splittermay comprise an infrared, red, green, blue quad dichroic. Thebeamsplitter reflects blue light capable of exciting fluorescein dye andtransmits the resulting reflected light from the eye to the consumercamera. The module optical system [2] may further comprise a rearconverging lens [9], wherein the rear converging lens [9] opticallycouples an illumination optical path [24] to an imaging acquisition path[23], and wherein the module optical system [2] may further comprise alight trap [6] disposed above the beam splitter [7] whereby lightpassing through the beam splitter [7] along the illumination opticalpath [23] and not redirected along the module imaging optical path [24]is absorbed by the light trap [7]. The light trap [6] may be lined withat least one of light absorbing material, black absorbing felt,absorbing neutral density filter, or any combination thereof. The lighttrap [6] may further comprise walls which cause light to reflectinternally within the light trap [6]. The fundus camera may furthercomprise a housing [14] that includes the module optical system [2] andmay be configured to couple the module optical system [2] to theconsumer camera device [1]. The housing may be configured to allowdetachment from the consumer camera device [1] to enhancemanufacturability and maintenance of the fundus camera. The housing [14]may further comprise electrical circuitry [21] to interface the moduleoptical system [2] with the consumer camera [1]. The housing may furthercomprise a battery-based power source [20] or the like. The housing [14]may be in communication with the module interface system [15], having amount for the front camera device lens [35] of the consumer cameradevice [1] to maintain the front camera device lens [35] at a constantfocal distance for focusing on the image of the retina produced by thefront objective lens [4]. The fundus camera may comprise the housing[14] that comprises the module optical system [2]; a module interfacesystem [15] (e.g. macro lenses, physical coupling, macro extension ring)to integrate the module optical system [2] with the consumer cameradevice [1]; and wherein the housing [14] provides an optical barrierthat separates the illumination path [24] from the module imagingacquisition optical path [23], except between the beamsplitter [7] andthe redirecting mirror [8] of the illumination optical path [24]. Thehousing may be configured to allow detachment of the module illuminationpath [24] from the image acquisition path [23] to enhancemanufacturability and maintenance of the fundus camera. The moduleinterface system [15] may further comprise a macro extension lens [37]to enhance the consumer camera device [1] ability to focus on the imageof the retina produced by the consumer camera device [1]. The consumercamera device [1] may comprise a front camera device lens [35], whereinthe macro extension ring is positioned to place the central focal pointof the camera device front lens [35] at the location of the image formedby the front objective lens [4] for enhancing ability of the consumercamera device [1] to use its entire focal range both positive andnegative to allow it to focus on subjects with a range of eyeglassprescriptions. The module interface system [15] may further comprise amacro lens to enhance the consumer camera device's ability to focus onthe image of the retina produced by the consumer digital camera device[1]. The consumer camera device [1] may comprise a front camera devicelens [35], wherein the macro lens can be positioned to place the centralfocal point of the camera device front lens [35] at the location of theimage formed by the front objective lens [4] for enhancing ability ofthe consumer camera device [1] to use its entire focal range bothpositive and negative to allow it to focus on subjects with a range ofeyeglass prescriptions. The interface system [15] further comprises amacro extension ring, whereby the macro extension ring being integratedinto the housing [14] of the fundus camera to enhance manufacturabilityof the fundus camera. The image sensor [53] of the consumer cameradevice [1] may be of a reduced size to increase depth of field of thefundus camera to enhance the range of subject's refractions over whichthe fundus camera can focus to reduce the need for a manual diopteradjustment. The consumer camera device [1] may further comprises atleast one of: auto-focusing elements; auto-exposure elements; imagestabilization technology; means for taking macro images; image sensorsensitivity to infrared light through removal of infrared filter in theconsumer camera device [1] and replacement with filter that transmitsinfrared light; LCD for observing the image of the retina; flashillumination for enhancing image recorded by the consumer camera; datastorage system for recording of the image of the retina; or a custommode for storing camera configuration to enhance ease of use for fundusphotography (or any other component as provided, desired or required).The data storage system may further comprise a flash memory device (orother storage as desired or required) for storing images of the fundus.The fundus camera may further comprise a transmission module (or anytransmission means, circuit or channel as desired or required) forcommunication to a local and/or remote location. The transmission modulemay further comprise a network enabled wireless data transfer systemwith means for transferring recorded images of the fundus [5] to anindependent archival system (or other designated, required or desiredlocation or destination). The transmission module may further comprise acombination data storage device and wireless data transfer system. Thecombination data storage device and wireless data transfer system mayfurther comprise an Eye-fi card or the like. The local and/or remotelocation is at least one of a user, a processor, a display, a database,an archive, or any combination thereof. The transmission module mayprovide a means for the communication of images of the fundus to bereviewed by ophthalmologists or care provider in a remote location. Thefundus camera may further comprising an LCD screen (or any type ofdisplay or graphics). The LCD screen [51] may be configured to show alive image of the image on an image sensor [51] of the consumer cameradevice [1]. The LCD screen [51] may be a flip screen type that maycomprise a rotation mechanism configured to allow inversion ofhorizontal and vertical axes of the flip screen LCD. The flip screen[51] may further comprise capability to display a mirror image displayof the image on the image sensor [53] of the consumer camera device [1]to enhance ease of alignment of camera with the patients eye. The funduscamera according may further comprise an image processing module [55],wherein the consumer camera device comprising an image sensor [53]whereby the image processing module [55] may be configured to enhancethe image of the retina recorded by the image sensor [53] of theconsumer camera device [1]. The image processing module [55] may beconfigured to display a mirror image of the image of the retina on theimage sensor [53] of the consumer camera device [1]. The imageprocessing module [55] may be configured to separate the spectralwavelength content of the image of the retina recorded by the imagesensor [53]of the consumer camera device [1]. The image processingmodule [55] may further comprise a method for subtracting infraredspectral wavelength content of the image of the retina recorded by theimage sensor of the consumer camera device to produce a resultant imagethat comprises a subset of the spectral content of the image of theretina recorded by the image sensor [53] of the consumer camera device[1]. The subset of the spectral content may further comprise at leastone of: red free spectral content; infrared spectral content;ultraviolet spectral content; or visible spectral content. The imageprocessing module [55] may be configured to eliminate back lightreflections from the image of the retina recorded by the image sensor[53] of the consumer camera device [1]. The elimination of back lightreflections identifies the back light reflections from the retinal imagerecorded by the image sensor [53] of the consumer camera device [1] bycomparing the optical properties of the back light reflections with theoptical properties of the retinal image. The optical properties mayinclude at least one of spectral content, size, brightness, or contrast.The image processing module [55] may be configured to subtract theoptical properties of the back light reflections with the opticalproperties of the retinal image to remove the back light reflections andrestore the retinal image that is obscured by the back lightreflections. The image processing module [55] may be configured tocombine overlapping images of the retina recorded by the consumer cameradevice [1], wherein the back reflection is removed from the finalcombined image by choosing areas of each individual image that do notinclude the optical properties of the back reflections. The imageprocessing module [55] may be configured to store a mirror image of theimage from the image sensor [53] of the consumer camera device [1] tocorrect the inverted orientation of the image from the image sensor ofthe consumer camera device [1]. The image processing module [55] may beconfigured to adjust the exposure of the recorded image of the consumercamera device [1] to even the illumination across the image recorded ofthe consumer camera device [1]. The fundus camera according to claim 91,wherein the front objective lens [4] further comprises a multipleelement lens. The front objective lens [4] may be a single element lens.The single element lens may comprises at least one of the following: adouble aspheric lens; an aspheric convex lens; a convex-convex lens; ora convex-plano lens (or other lens as desired or required). The frontobjective lens [4] may comprise antireflection coatings to reduceillumination source reflections. The front objective lens [4] may besecured by a lens mount [59] with a front converging lens mask to thatmay be configured to reduce edge image artifacts from the frontobjective lens [4]. The front objective lens [4] may be a standard lensnormally used for indirect ophthalmoscopy. The front objective lens [4]may have an effective power of about 20 D to about 22 D (e.g., VolkDigital Clearfield lens or an Ocular Instruments OI-22M lens) to provideabout 50° field of view of the fundus [5]. The fundus camera accordingmay further comprise a polarizer means, device or system for polarizinglight to reduce back light reflections from the fundus camera [2]. Thepolarizer means comprising a first polarizer [41] may be placed in theimage illumination optical path [24] and a second polarizer [43] may beplaced in the image acquisition optical path [23]. The first polarizer[41] and/or the second polarizer [43] may be film polarizer type. Thefirst polarizer [42] and/or the second polarizer [43] may be wire gridpolarizer type. The first polarizer [41] and/or the second polarizer[43] may be oriented at different angles relative to one another. Thefirst polarizer [41] and/or the second polarizers [43] may be orientedat about 90 degrees to one another to enhance cross polarization toreduce back light reflections from the fundus camera. The firstpolarizer [41] and/or the second polarizer [43] may be placed after theimage mask [10] and between the beamsplitter [7] and front lens [35] ofthe consumer camera device [2]. The second polarizer [43] may comprise acircle [44] of dimensions needed to cross polarize only the reflectionfrom the front objective lens [4] to reduce back light reflections fromthe front objective lens [4]. The second polarizer [43] may furthercomprise a combination of polarizer's oriented at different anglesrelative to one another. The second polarizer [43] may comprise one of asmaller polarizer in the shape of a small circle [44], and one of alarger polarizer [46] with a small circle cut from the center of thelarger polarizer, wherein the smaller circle polarizer [44] may bepositioned before the larger polarizer at the location of the small cutcircle, or is positioned within the small cut circle of the largerpolarizer, and wherein the smaller circle polarizer may be oriented atabout 90 degrees to the first polarizer [41] and larger polarizer isoriented in the same orientation as the first polarizer [41]. Thepolarizer means may comprise a linear polarizer (or other type asdesired or required). The polarizer means may comprise circularpolarizers.

The devices, systems, devices, compositions, computer program products,and methods of various embodiments of the invention disclosed herein mayutilize aspects disclosed in the following references, applications,publications and patents and which are hereby incorporated by referenceherein in their entirety:

1. U.S. Pat. No. 5,543,865, Nanjo, T., “Fundus Camera with PartiallyCommon Coaxial Observation and Photographing Optical Systems”, Aug. 6,1996.

2. U.S. Pat. No. 5,668,865, Duttweiler, et al., “Echo Canceler E-SideSpeech Detector”, Sep. 16, 1997.

3. International Patent Application Publication No. WO 2009/098516 A2,Adrian, P., “Camera Adapter Based Optical Imaging Apparatus”, Aug. 13,2009.

4. U.S. Pat. No. 7,048,379 B2, Miller, et al., “Imaging Lens andIllumination System”, May 23, 2006.

5. U.S. Pat. No. 4,266,861, Sawa, S., “Eye Fundus Camera”, May 12, 1981.

6. U.S. Patent Application Publication No. US 2008/0231803 A1, Feldon,et al., “Compact Ocular Fundus Camera”, Sep. 25, 2008.

7. U.S. Pat. No. 6,546,198 B2, Ohtsuka, H., “Fundus Camera forDiagnostic Fundus Photographing”, Apr. 8, 2003.

8. U.S. Pat. No. 7,364,297 B2, Goldfain, et al., “Digital DocumentingOphthalmoscope”, Apr. 29, 2008.

9. European Patent Application Publication No. EP 1 354 551 A1, Sugino,et al., “Ophthalmologic Photographing Apparatus”, Oct. 22, 2003.

10. U.S. Patent Application Publication No. US 2009/0201467 A1, Smith,et al., “Fundus Photo-Stimulation System and Method”, Aug. 13, 2009.

11. U.S. Pat. No. 4,257,688, Matsumura, I., “Eye Examining Instrument”,Mar. 24, 1981.

12. U.S. Pat. No. 5,764,341, Fujieda, et al., “Ophthalmic Apparatus”,Jun. 9, 1998.

13. U.S. Pat. No. 7,118,218 B2, “Barker, et al., “Method and Device forImaging a Section of the Eyeground”, Oct. 10, 2006.

14. U.S. Pat. No. 7,481,534 B2, Fink, W., “Optomechanical and DigitalOcular Sensor Reader Systems”, Jan. 27, 2009.

15. Chalam, K., et al., “Evaluation of Modified Portable Digital Camerafor Screening of Diabetic Retinopathy”, Ophthalmic Res. 2009; 41:60-62.

16. International Patent Application Publication No. WO 2006/013579 A1,Gupta, S., “A Retinal or Fundus Camera”, Feb. 9, 2006.

17. International Patent Application Publication No. WO 2006/086269 A2,Collins, C., et al., “Hand Held Device and Methods for Examining aPatient's Retina”, Aug. 17, 2006 (International Application No.PCT/US2006/004031, filed Feb. 6, 2006).

18. International Patent Application Ser. No. PCT/US2010/033875,entitled “Self-Illuminated Handheld Lens for Retinal Examination andPhotography and Related Method Thereof,” filed May 6, 2010.

Unless clearly specified to the contrary, there is no requirement forany particular described or illustrated activity or element, anyparticular sequence or such activities, any particular size, speed,material, duration, contour, dimension or frequency, or any particularlyinterrelationship of such elements. Moreover, any activity can berepeated, any activity can be performed by multiple entities, and/or anyelement can be duplicated. Further, any activity or element can beexcluded, the sequence of activities can vary, and/or theinterrelationship of elements can vary. It should be appreciated thataspects of embodiments of the present invention may have a variety ofsizes, contours, shapes, compositions and materials as desired orrequired.

In summary, while the present invention has been described with respectto specific embodiments, many modifications, variations, alterations,substitutions, and equivalents will be apparent to those skilled in theart. The present invention is not to be limited in scope by the specificembodiment described herein. Indeed, various modifications of thepresent invention, in addition to those described herein, will beapparent to those of skill in the art from the foregoing description andaccompanying drawings. Accordingly, the invention is to be considered aslimited only by the spirit and scope of the following claims, includingall modifications and equivalents.

Still other embodiments will become readily apparent to those skilled inthis art from reading the above-recited detailed description anddrawings of certain exemplary embodiments. It should be understood thatnumerous variations, modifications, and additional embodiments arepossible, and accordingly, all such variations, modifications, andembodiments are to be regarded as being within the spirit and scope ofthis application. For example, regardless of the content of any portion(e.g., title, field, background, summary, abstract, drawing figure,etc.) of this application, unless clearly specified to the contrary,there is no requirement for the inclusion in any claim herein or of anyapplication claiming priority hereto of any particular described orillustrated activity or element, any particular sequence of suchactivities, or any particular interrelationship of such elements.Moreover, any activity can be repeated, any activity can be performed bymultiple entities, and/or any element can be duplicated. Further, anyactivity or element can be excluded, the sequence of activities canvary, and/or the interrelationship of elements can vary. Unless clearlyspecified to the contrary, there is no requirement for any particulardescribed or illustrated activity or element, any particular sequence orsuch activities, any particular size, speed, material, dimension orfrequency, or any particularly interrelationship of such elements.Accordingly, the descriptions and drawings are to be regarded asillustrative in nature, and not as restrictive. Moreover, when anynumber or range is described herein, unless clearly stated otherwise,that number or range is approximate. When any range is described herein,unless clearly stated otherwise, that range includes all values thereinand all sub ranges therein. Any information in any material (e.g., aUnited States/foreign patent, United States/foreign patent application,book, article, etc.) that has been incorporated by reference herein, isonly incorporated by reference to the extent that no conflict existsbetween such information and the other statements and drawings set forthherein. In the event of such conflict, including a conflict that wouldrender invalid any claim herein or seeking priority hereto, then anysuch conflicting information in such incorporated by reference materialis specifically not incorporated by reference herein.

We claim:
 1. A method for removing non-retinal ophthalmic reflectionsfrom a retinal image, the method comprising: obtaining informationcomprising a first retinal image from a camera device; identifying anon-retinal ophthalmic reflection in the information comprising thefirst retinal image by automatically determining differences in theoptical properties of the non-retinal ophthalmic reflection from thefirst retinal image compared to the optical properties of the firstretinal image that do not contain the non-retinal ophthalmic reflection;using the identified non-retinal ophthalmic reflection, automaticallyconstructing a digital mask that corresponds to areas of the firstretinal image containing the non-retinal ophthalmic reflection; andremoving the non-retinal ophthalmic reflection by digitally applying themask to the first retinal image to provide a digitally-masked retinalimage.
 2. The method of claim 1, wherein removing the non-retinalophthalmic reflection by digitally applying the mask to the firstretinal image includes subtracting values in the digital mask fromvalues in the first retinal image at corresponding locations in thedigital mask and the first retinal image.
 3. The method of claim 1,wherein removing the non-retinal ophthalmic reflection by digitallyapplying the mask to the first retinal image includes subtracting valuescorresponding to a spectral signature of the non-retinal ophthalmicreflection from the first retinal image.
 4. The method of claim 1,wherein identifying the non-retinal ophthalmic reflection in the firstretinal image includes using information about at least one opticalproperty comprising a spectral wavelength content, a size, a brightness,a contrast, or a hue of a region containing the non-retinal reflectionas compared to at least one corresponding optical property of the firstretinal image that lacks the non-retinal ophthalmic reflection.
 5. Themethod of claim 4, wherein identifying the non-retinal ophthalmicreflection in the first retinal image includes using pixel informationin one or more color channels of the first retinal image.
 6. The methodof claim 5, wherein the pixel information is used from a blue channel ofthe first retinal image.
 7. The method of claim 1, wherein thenon-retinal ophthalmic reflection comprises Purkinje reflections from acornea and a lens of an eye being imaged by the camera device.
 8. Themethod of claim 1, wherein the non-retinal ophthalmic reflectioncomprises scattered light from a cornea and a lens of an eye beingimaged by the camera device.
 9. The method of claim 1, wherein thenon-retinal ophthalmic reflection comprises light scattered within thecamera device.
 10. The method of claim 1, wherein the non-retinalophthalmic reflection comprises reflections from imaging optics withinthe camera device.
 11. The method of claim 1, wherein the identifyingthe non-retinal ophthalmic reflection, automatically constructing thedigital mask, and removing the non-retinal ophthalmic reflection bydigitally applying the mask to the first retinal image are performedremotely with respect to the camera device.
 12. The method of claim 1,wherein the identifying the non-retinal ophthalmic reflection,automatically constructing the digital mask, and removing thenon-retinal ophthalmic reflection by digitally applying the mask to thefirst retinal image are performed using a processor included as aportion of the camera device.
 13. A method to remove non-retinalophthalmic reflection from at least one retinal image amongst aplurality of retinal images and to create a blended composite of theretinal images, the method comprising: obtaining information comprisinga plurality retinal images of a subject from a camera device, theplurality of retinal images obtained under similar illumination andcorresponding to regions that overlap; identifying a non-retinalophthalmic reflection in at least one image amongst the plurality ofretinal images by automatically determining differences in the opticalproperties of the non-retinal ophthalmic reflection from the at leastone image compared to a retinal ophthalmic reflection; using theidentified non-retinal ophthalmic reflection, identifying a second imageamongst the plurality of images that does not contain the non-retinalophthalmic reflection in the same region; automatically constructing adigital mask that corresponds to the region of the at least one retinalimage containing the non-retinal ophthalmic reflection; removing thenon-retinal ophthalmic reflection by digitally applying data from thesecond image in the same region defined by the mask to the at least oneretinal image to provide a digitally-masked retinal image; andaggregating the retinal images including the digitally-masked retinalimage to generate a composite for presentation to a user.
 14. The methodof claim 13, wherein removing the non-retinal ophthalmic reflection bydigitally applying the mask to at least one the retinal image includessubtracting values in the digital mask from values in the at least oneretinal image at corresponding locations in the digital mask and the atleast one retinal image.
 15. The method of claim 13, wherein removingthe non-retinal ophthalmic reflection by digitally applying the mask tothe at least one retinal image includes subtracting values correspondingto a spectral signature of the non-retinal ophthalmic reflection fromthe at least one retinal image.
 16. The method of claim 13, whereinidentifying the non-retinal ophthalmic reflection in the at least oneretinal image includes using information about at least one opticalproperty comprising a spectral wavelength content, a size, a brightness,a contrast, or a hue of a region containing the non-retinal reflectionas compared to at least one corresponding optical property of the atleast one retinal image that lacks the non-retinal ophthalmicreflection.
 17. The method of claim 13, wherein identifying thenon-retinal ophthalmic reflection in the at least one retinal imageincludes using pixel information in one or more color channels of the atleast one retinal image.
 18. The method of claim 17, wherein the pixelinformation is used from a blue channel of the at least one retinalimage.
 19. The method of claim 13, wherein an area of the at least oneretinal image containing the non-retinal ophthalmic reflection isreplaced in the composite with a corresponding overlapping area from atleast one other retinal image that lacks the non-retinal ophthalmicreflection amongst the plurality of retinal images.
 20. The method ofclaim 13, comprising adjusting an exposure value used for acquisition ofthe at least one retinal image to provide even illumination across thecomposite when the retinal image is aggregated.